... steel 1.The service life of O-Ring or X-Ring Chain is greatly depended on the wearing between ... shaft and the sleeve. The "O" ring or “X” ring will greatly reduce the wearing and thus prolongthe service ... 530V, 530VM, 630V, 630VM,428V-X,428VM-X,520V-X,525V-X,530V-X,530VM-X,630V-X,630VM-X,420HZ,428HZ,520NZ,525HZ,530HZ,630HT3.Color ... grease is made in USA.6.O-ring and X-ring are made in Tianwan.7.The chains ...