Heavy Duty Performance Swivel Feet Adjusters feature a large foot print that covers the valve stem to reduce the chance of mushrooming and side load friction. Contact areas are precision ground and hardened. Features slotted screw head design. Kit is complete with rocker boss shims to insure correct rocker arm geometry. Set of 8. Will work for all Type 1 engines, and Bus engines up thru 71. 21-1707