# Grand Design Momentum M-Class 398M

M-Class 398M is a fifth wheel floor plan by Momentum (Grand Design).

## Specs (2025 model year)

| Spec | Value |
| --- | --- |
| Length | 43 ft 10 in |
| Sleeps | 11 |
| Slide-outs | 0 |
| GVWR | 20,000 lbs |
| MSRP | $135,055 |

## Model years

2025, 2024, 2023. Year-specific specs: `https://rvenvy.com/fifth-wheel-trailers/grand-design/momentum/m-class-398m?year={year}`

## Overview

The 18-foot garage is the headliner here — big enough for serious toys, and thoughtfully equipped with its own dedicated AC unit to keep things comfortable after a long ride. Inside the living quarters, the 398M goes beyond basic with a sunken tub with a seat, heated couch, and dual-pane windows throughout. Three AC units total mean everyone stays cool no matter where they're hanging out. Owners consistently call it out for its livability on extended trips, and with sleeping for 11, it's built to bring the whole crew along.

## Inventory

No units currently for sale. Search similar inventory: https://rvenvy.com/inventory

Floor plan diagram: https://images.rvenvy.com/3fa4c77bd972a61276057ccd12ce2c0769cf4c905d68bdd463d75dea1fa64f5f/1024.webp

Canonical page: https://rvenvy.com/fifth-wheel-trailers/grand-design/momentum/m-class-398m