Tillett is the original aftermarket kart seat manufacturer and the only seat we recommend in place of the OEM seat for OTK karts.  The T11VG is nearly identical in dimension to the OEM OTK seat but it is a soft rigidity which gives extra grip.  This is the seat used by Msquared drivers Mike Beeny, Bonnier Moulton and Tyler Bennett.  For those who cannot tolerate the relatively low side bolsters of the OTK seat, we recommend the T9T which is a deeper (more comfortable) seat.