+35 - SALE PRICE: $149,995
- MSRP: $196,938
- You Save: $46,943
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45ft long
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19,170 lbs
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Sleeps 4
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3 slides
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Kitchen IslandTwo Entry/Exit Doors
399M Floorplan
Specifications
| Sleeps | 4 | Slides | 3 |
| Length | 44 ft 10 in | Ext Width | 8 ft 5 in |
| Ext Height | 13 ft 6 in | Int Height | 8 ft 5 in |
| Hitch Weight | 3406 lbs | GVWR | 23500 lbs |
| Dry Weight | 19170 lbs | Fresh Water Capacity | 140 gals |
| Grey Water Capacity | 104 gals | Black Water Capacity | 52 gals |
| Tire Size | 17.5" | Furnace BTU | 35000 btu |
| Fuel Capacity | 60 gals | Available Beds | Queen |
| Refrigerator Type | 12V Stainless Steel | Refrigerator Size | 20 cu ft |
| Cooktop Burners | 3 | Number of Awnings | 3 |
| Axle Weight | 7000 lbs | Garage Size | 12 ft 6 in |
| LP Tank Capacity | 30 lbs | Water Heater Type | On Demand |
| AC BTU | 30000 btu | TV Info | LR 50" LED TV, Garage 32" LED TV, Patio 65" TV |
| Awning Info | 9', 12', 14' Power w/LED Lights | Axle Count | 3 |
| Washer/Dryer Available | Yes | Number of LP Tanks | 2 |
| Shower Type | Shower w/Seat | Electrical Service | 50 amp |
| VIN | 573FM4737TBB04656 |
Description
The 2026 Grand Design Momentum 399M is a premium luxury toy hauler fifth wheel built for RVers who want a true combination of residential living space, large garage flexibility, and high-end extended-season construction. At approximately 44’10”–45’ in length with a dry weight around 18,000 lbs and a GVWR of 22,500–23,500 lbs, this model sits in the upper tier of the Momentum lineup and is designed for serious travelers who still want upscale comfort at camp.
Inside, the 399M stands out because it’s not just a traditional toy hauler—it’s designed as a “flex-living” platform where the rear garage can function as a cargo space, office, lounge, or additional sleeping area depending on your needs. The garage includes a large ramp door that converts into a patio deck, extending your living space outdoors and creating a second entertainment zone beyond the main cabin.
The main living area feels more like a modern apartment than a garage-based RV, featuring opposing slide-outs, theater seating, a sofa, and a residential entertainment center with a fireplace. A central kitchen island anchors the space, giving you real countertop workspace, while large windows throughout the slide-outs bring in natural light and open up the interior when fully set up.
The kitchen is built for full-time travel use, offering a large residential refrigerator (up to ~20 cu. ft.), 3-burner cooktop, oven, microwave, and deep sink with solid-surface countertops, plus a full pantry for extended trips. This makes it easy to cook for families or groups without relying on campground amenities.
Up front, the private master bedroom includes a queen bed slide (king optional), wardrobe storage, and washer/dryer prep, giving owners a true residential retreat. The adjacent bathroom includes a large walk-in shower, porcelain toilet, and vanity storage, designed for comfortable daily use even during long-term stays.
One of the defining strengths of the Momentum 399M is its dual-living-zone design, separating the garage and main coach so multiple groups can coexist without feeling crowded. The garage itself can include a half bath, additional sleeping options, and entertainment setup, making it extremely versatile for families, toy haulers, or mobile lifestyle users.
Built on Grand Design’s Momentum platform, the 399M features laminated fiberglass construction, a fully enclosed and heated underbelly, and heavy-duty triple-axle running gear, making it capable of extended-season camping and demanding road travel. Exterior highlights typically include multiple power awnings with LED lighting, a 6-point hydraulic leveling system, and large pass-through storage, ensuring easy setup and strong campsite stability.
Reasons to Buy the 2026 Momentum 399M
- Massive garage-to-patio conversion for indoor/outdoor living
- True flex space garage (toy storage, office, lounge, or bedroom)
- Spacious residential-style main living area with opposing slides
- Large kitchen island with residential appliances
- Sleeps up to ~5–6 depending on configuration
- Private master bedroom with washer/dryer prep
- Garage half bath option for added convenience
- Triple-axle stability for heavy-duty towing
- Heated and enclosed underbelly for extended-season use
- Premium Grand Design construction and resale value
Why Buy from Lazydays RV Powered by Campers Inn RV
- Large selection of Grand Design Momentum luxury toy haulers
- Competitive financing options for qualified buyers
- Factory-trained RV technicians and nationwide service network
- Trade-in assistance for easy upgrades
- Full delivery walkthrough and orientation before departure
- Trusted national RV dealership group with long-term support
Features
Standard Features (2026)
Exterior
- Keyed Alike™ Ramp Door Latches
- 2nd Patio Awning w/ LED Lights
- 3rd Awning w/ LED Lights
- Exterior Color Changing LED Accent Lighting
- High-Gloss Gel Coat Exterior Sidewalls
- Door Side Exterior Spray Port
- Frameless Tinted Windows
- Walk-On Roof
- 17.5" Spare Tire (Undermount)
- MORryde Strut Assist Entry Step
- Slam-Latch Baggage Doors
- Mo Secure
- Gen III 3 Seasons Doors (Opt)
Construction
- 101" Wide Body Construction
- 5-Side Aluminum Cage Construction
- Fully Enclosed and Heated, Underbelly and Storage Area
Running Gear
- Upgraded Axle Hangers
- Heavy Duty H-Rated Tires
- Heavy Duty 7,000 lb. Axles with ABS Brakes
- 17.5" H-Rated Aluminum Wheels
- MORryde® Independent Suspension 2.0
Frame & Chassis
- 6-Point Hydraulic Leveling System
- MORryde® Pin Box
- 101" Wide Body Super Chassis w/Drop-Frame Storage
Interior
- Interior Color Changing LED Accent Lighting
- Hardwood Cabinet Doors w/Hidden Hinges
- Recliner Sofa w/Adjustable Headrest or Flip Down Cupholders
- Central Vacuum System w/ Tools and Dust Pan
- Plywood Drawer Bottoms
Kitchen
- Microwave
- Professional Grade Stainless Steel Cooktop
- 12-Volt High Power MaxxAir w/Rain Sensor
- Window Behind Range
- Kitchen Barstools w/ Extended Countertops
- Smart Sink w/Removable Cutting Board, Produce Strainer and Glass Rinser
Electrical
- Solar Prep (10-gauge wiring with universal MC4 connectors)
- 75 Amp Converter
- 12V Battery Disconnect
HVAC
- 12V High Power Fan (Kitchen)
- 35k BTU High-Capacity Furnace
- Fireplace w/ 5,000 BTU Electric Heater
- StealthAC Smart AC System
- Attic Vent
- High-Capacity Heat Ducts
Plumbing
- Exterior Spray Port (Door Side)
- 12V Tank Heaters
- Sewer Hose Storage Area
- Whole House Water Filtration System
- All-In-One Enclosed and Heated Utility Center
Bedroom
- Under Bed Storage Area
- Individually Switched Reading Lights Over Bed
- Bedside 110-Volt & USB Outlets
- Window Above Master Bed Headboard
- 60" X 80" Queen Bed Pillow Top Bed Mattress
Bathroom
- Skylight Above Shower
- Porcelain Toilet
- Medicine Cabinet w/Mirrored Door (N/A 410TH)
- Undermount Lav Sink
- One-Piece Fiberglass Shower w/Glass Door & Teak Bench Seat
Appliance
- Fireplace with Electric Heater
- Stainless Steel 20 Cu. Ft. Refrigerator
- 30" Over-The-Range Microwave
Electronics
- OneControl™ System
- Back-Up Camera Prep
- Exterior Cable/SAT Plug-In
- LED Smart TV in Living Area
- LED TV in Bedroom
- Rockford Fosgate Stereo Entertainment System w/HDMI and App Controls
- Exterior Speakers
- No-Crank Digital TV Antenna w/Booster
- LED TV in Garage
- OmniConnect On-Board WiFi Ready
Packages
Exterior Package
- Satellite TV Prep
- MORryde Strut Assist Entry Step
- Aluminum Quad Entry Steps - Garage Entry
- 7,000 lb. Axles w/Self Adjusting Brakes, Wet Bolts and Bronze Bushings
- 17” Aluminum Wheels (120PSI Rated)
- Cooper Tires® 17.5" All-Steel H-Rated Tires
- Slam-Latch Baggage Doors
- Frameless Tinted Windows
- Exterior Security Lights
- Power Patio Awning w/LED Lighting
- Folding Roof Ladder
- White Gel Coat Fiberglass Front Cap
- 12V Battery Disconnect
- All-In-One Exterior Utility Center
- 50 Amp Service
- Converter
- Enclosed Fuel Station w/ Dual Fuel Tank
- Partial Paint Gel Coat Fiberglass Front Cap
Luxury Interior Package
- 49" Class LED TV in Living Area
- Stereo Entertainment System w/Bluetooth and App Based Controls in Living Area
- Washer/Dryer Prep
- On Demand Water Heater
- Roller Shade Window Coverings (Main Living Area and Bedroom)
- Recessed LED Puck Lighting
- Solid Surface Countertops w/ Sink Covers
- Stainless Steel Undermount Kitchen Sink
- Chef Inspired Range & Oven w/ Cover
- Kitchen Pantry w/ LED Light Strip
- Garage Control Panel
Garage package
- 32" Class LED TV in Garage
- Protective Diamond Plate on Garage Sidewalls
- 2,500 lb Rated Flush-Mount Tie-Downs
- Ram-Air Garage Vents on Both Sides
- Tuff-Ply Gas and Oil Resistant Garage Flooring
- FastRamp™ Rear Ramp Door
- Triple Insulated Garage Floor
Weather-Tek Package
- R-Value Equivalent (R-40 Roof / R-45 Floor / R-11 Sidewalls / R-40 Garage Floor / R-24 Slide room Floor)
- Fully Enclosed and Heated, Underbelly and Storage Area
- Enclosed and Heated Low Point Drains
- Engineered Underbelly Airflow Heat Paths
- Stealth AC System w/ Insulated A/C Ducts
- Attic Vent
- Plumbing Line Insulation Barrier
See us for a complete list of features and available options!
All standard features and specifications are subject to change.
All warranty info is typically reserved for new units and is subject to specific terms and conditions. See us for more details.
Due to the current environment, our features and options are subject to change due to material availability.
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*All calculated monthly payments are an estimate for qualified buyers only and do not constitute a commitment that financing or a specific interest rate or term is available. Financing terms may not be available in all Campers Inn locations. Campers Inn RV Sales is not responsible for any misprints, typos, or errors found in our website pages. Any price listed excludes sales tax, registration tags, and delivery fees. Manufacturer pictures, specifications, and features may be used in place of actual inventory in stock on our lot. Please contact us for availability as our inventory changes rapidly.
Manufacturer and/or stock photographs may be used and may not be representative of the particular unit being viewed. Where an image has a stock image indicator, please confirm specific unit details with your dealer representative.
Manufacturer and/or stock photographs may be used and may not be representative of the particular unit being viewed. Where an image has a stock image indicator, please confirm specific unit details with your dealer representative.