Mark 1 and Mark 2 Sprites had a single piston cylinder on the rear brakes around 1964 or 65, 1098 Sprites were upgraded to dual piston rear cylinders. Some early Sprites have been upgraded to this rear back plate to allow fitment of the dual rear wheel cylinders on early cars. If you car has been upgraded to dual piston rear cylinders this is the product you need to restore your rear brakes. If you have the early single piston rear wheel cylinder you can buy that here . If you're unfamiliar check out the link below which will help you choose which type you need.