{"@context":"https://schema.org","@type":"Product","name":"2 Grand Design Momentum M-Class RVs for sale","offers":{"@type":"AggregateOffer","offerCount":2,"lowPrice":"129999.00","highPrice":"139989.00","priceCurrency":"USD","offers":[{"@type":"Offer","url":"https://www.rvt.com/buy/details/2026-grand-design-momentum-m-class-399m/333bf889-d4da-11f0-beaa-02c8259c7411/","itemOffered":{"@type":"Thing","name":"2026 GRAND DESIGN MOMENTUM M-CLASS 399M","description":"2026 Grand Design Momentum 399M, 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/outdoo","itemCondition":"Used","priceCurrency":"USD","price":"129999.00"}},{"@type":"Offer","url":"https://www.rvt.com/buy/details/2026-grand-design-momentum-m-class-399m/48123aac-2814-11f1-9d95-02ea7b77d8a7/","itemOffered":{"@type":"Thing","name":"2026 GRAND DESIGN MOMENTUM M-CLASS 399M","description":"2026 Grand Design Momentum 399M, The 2026 Grand Design Momentum 399M is a luxury fifth-wheel toy hauler designed around flexible garage living, residential comfort, and extended-season durability. It s built for RVers who want the ability to haul toys, create a second living space, or simply enjoy a large rear flex room while still having a high-end, apartment-style main coach. At approximately 44 10 in length with a dry weight around 19,170 lbs and a GVWR of 23,500 lbs, it sits near the top of the Momentum lineup for size, capability, and premium features.

Inside, the 399M is all about versatility. Instead of a traditional fixed garage, the rear area is designed as a multi-use flex space that can function as a garage, lounge, office, guest room, or entertainment zone depending on how you travel. One of its signature features is the rear Party Patio system, which converts into an outdoor entertainment deck with integrated appliances and a large exterior entertainment wall effectively giving you a second living room outside the RV.

The main living area feels like a modern residential loft. With triple slide-outs, the center space opens up dramatically to include theater seating, a sofa, and a large entertainment center with fireplace. The layout is designed so that everyone in the coach can gather comfortably without feeling crowded, even on longer stays.

The kitchen is positioned as the heart of the coach, featuring a residential-style refrigerator (up to ~20 cu. ft.), 3-burner cooktop, oven, microwave, pantry storage, and a full countertop workspace, often with bar seating or a dinette that doubles as a work area. This makes the 399M especially popular with long-term travelers who want full cooking capability on the road.

Up front, the private master suite includes a queen or optional king bed, wardrobe storage, and washer/dryer prep, giving it a true residential bedroom feel. The adjoining bathroom features a large walk-in shower, porcelain toilet, and vanity storage, designed for extended use rather than weekend camping.

From a construction standpoint, the 399M is built on Grand Design s heavy-duty Momentum platform, including 101 wide-body construction, laminated fiberglass walls, triple axles, and a fully enclosed and heated underbelly for extended-season camping. It also includes a 6-point hydraulic leveling system, multiple power awnings, and large pass-through storage, making setup and campsite living easier despite its size.

Reasons to Buy the 2026 Momentum 399M Unique garage-to-living flex space design Rear Party Patio outdoor entertainment system Bar/Dinette Swivel Table Spacious residential main living area with triple slides Full kitchen with residential refrigerator and pantry storage Private master bedroom with washer/dryer prep ","itemCondition":"Used","priceCurrency":"USD","price":"139989.00"}}]}}

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Grand Design Momentum M-Class RVs for sale