Rockwood Products‘ Original Seat Base Adapter Plates are 3/4-inch thick billet aluminum with polished stainless steel covers, which allow the seat to be bolted to the floor without drilling new holes. The plates allow for the seat to be moved back by 2- or 4-inches, depending on a driver’s preference. This moves the suspension box for the seat back for more leg room. The plates are made for Sears Atlas, Bostrom, National and Seats Inc. seats, and fit in most Peterbilt and Kenworth trucks.