These tappets are nitrided to increase face surface hardness to minimum RC58 for increased wear resistance. An oil drain hole in the side aids lubrication of the face. I resurface face of each tappet to provide a smoother finish and to make sure the face is perpendicular to the side walls and flat for proper interface with the cam lobe. I hand select the tappets with a narrow enough edge chamfer to accommodate high velocity lobe profiles such as GP2 and GP3 where the contact patch reaches close to the edge of the tappet. These select tappets are sold as SKU 462. The tappets with a wider chamfer are sold at a lower price as SKU 462B for use with original cam profiles where the contact patch does not reach as close to the edge. There is no harm in using SKU 462 tappets with an original cam profile but when available, you can save money by using SKU 462B.
Good Parts recommends always replacing the tappets when replacing a camshaft.
Price is per each tappet.