The D. I. D ERV7 X-ring chain is the ultimate high-performance, lightweight, low-friction sealed ring race chain available. An improvement from the ERV3, the ERV7 boasts lots of upgrades, including an 11% longer chain life. D. I. D has upgraded the materials of the pin, bushing, inner/outer plates, and the patented X-Ring seal, increasing wear resistance and reducing friction. Weight per 100 Links: 3. 41 lbs. ; Tensile Strength: 8, 800 Lbs. ; Maximum engine displacement: 1000cc. Rivet Type Master link included. D. I. D's patented X-ring construction reduces friction by twisting between the side plates instead of being squashed. Other makers modified O-rings have squashed points that increase friction. The twisting action of the X-ring disperses the pressure and minimizes power loss, while the four contact points greatly increase its sealing performance. This keeps the dirt out and the lubrication in much better than any other O-ring. X-rings have the greatest wear resistance of any other type of O-ring or non-O-ring chain.