Set of 10 fuel injector sealing washers. Also know as heat shield crush washers. Fit 1984 to 1999 Mercedes aluminum head 60x. diesel engines 4, 5, and 6 cylinder (190D, 300D, 300TD 300D 2.5 300SDL 350SD S350 and E300D). For best performance these must be change every time you remove your injectors to clean or replace. If you have a four cylinder order 2 packs. That will give you a total of 20 or 5 injector service cycles. If you have a 6 cylinder order 3 packs for 5 injector service cycles.