01-13 YAMAHA YZ250F: Factory Effex The Bump Seat Foam (Suzuki/Yamaha) They all ride at Factory Effex and they put that experience into every product they sell. Every Factory Effex product is created from passion and pride, built to be the best. It's the only way they know how to do it. The first conform fitting seat bump specifically designed for 4-strokes that can be used on any seat application. Features Tri-density Soft-cell seat foam technology that keeps you positioned on the seat where you need to be.