O -shaped sealing rolls roll the chain replacement dimensions that meet the ISO standard and match the standard sprocket; the O -shaped sealing ring is installed between the external and interior boards The environment that is suitable for abrasion resistance is high and cannot be lubricated frequently. Under the test state, the 0 -shaped sealing roller rolling chain wear resistance is only 10 times that of the initial lubrication standard roller chain. Agricultural machinery, motorcycle and other opening transmission.