Mustang One-Piece Extreme Fastback Seat For Harley Softail Fat Boy The new Extreme Fastback One-Piece Seat from Mustang makes a bold, no-nonsense statement, just like your Fat Boy. A low-cut 11.5 driver bucket is paired with a tall tail section for incredible back support, while giving a mean racing-cowl look, uniquely styled for the lines of the Fat Boy. The hand-sewn cover features a double-diamond pattern in front with a perforated-look vinyl on the 7 wide rear. Go bold and ride free in the comfort of the new Extreme Fastback. Features: 11.5 wide bucketed rider area provides excellent support in a low-profile, sporty package, with a 7 wide rear section. Handsewn cover with double-diamond and perforated accents made from marine-grade expanded vinyl Mustangs proprietary controlled-density foam formula requires no break-in and retains shape and support after years of use Marine-grade fiberglass baseplate for long-lasting support and durability, with polyurethane bumpers to absorb vibration