For Sale: Miscellaneous / Oklahoma City, Ok The Momentum By Grand Design Is All You Have Come To Expect From Grand Design Rv, And Then More. This Luxurious Toy Hauler Is Sure To Turn Heads, But The Beauty Of The Grand Design Momentum Toy Hauler Is Definitely More Than Skin Deep. It Is A True Four Seasons Couch With The Weather-tek Seal, Meaning In Test Of Weather Above 110 Degrees Fahrenheit And Below -4 Degrees Fahrenheit, The Momentum Exceeded Industries Standards By Average Temperatures In All 3 Areas Of The Coach In The 70's.