Rowing Machine Seat Cushion fits Perfectly Over Concept 2 Rower - Rower Seat Cushion Compatible with Hydrow, Concept2 and Other Row Machines - Rowing Accessories and Seat Pad. Fits Perfectly On The Concept 2 Rowing Machine: This black seat cushion is designed to have the exact specifications of the Concept 2 rowing machine's seat in mind - so it's a perfect, snug fit.