Thin wall thickness is the most important peculiarity of the SF-4 Bush series. They are light and compact, The inner-layer of the bush being a kind of high density copper alloy of special compositions, there is no hole and pit and provides higher load capacity and fatigue strength, in compare with traditional casting bronze bushes. It is manufactured by advanced technology and machinery, various kinds of lubricating indentations or grooves may be readily provided on the sliding surface, and so the re-oiling period is remarkably prolonged and the service lift is accordingly prolonged. It's used in agricultural machinery, construction machinery as well as engineering machinery etc.