The Sparco seat base allows you to bolt a Sparco seat into your car. They will bolt into the factory location, and gives a Sparco specific mounting pattern so that your seats line up properly. Reclining seats are able to bolt directly to this base, or a set of sliders. Fixed back seats may require a set of side mounts (depends on the seat) to be able to mount to this base properly. 

A new seat belt bolt may be necessary for installing the factory seat belt with this base