RK 520 XSO RX-Ring Chain - 104 Links , Chain Type: 520, Chain Length: 104, Chain Application: All 520XSO104 Pro X-ring chain lasts five to eight times longer than standard chain Provides two more lubricant pools than conventional O-rings for longer life Lubricated with specially formulated, vacuum-injected U-grease; locked in by tough Nitrile Butadine rubber X rings Polished and shot-peened link plates High tensile strength ensures reliable performance