"D.I.D 520 NZ Super Non O-Ring Chain - 114 Links The NZ series features our exclusive SDH Pin Treatment for Superor Strentgh and Long Life. The SDH pin treatment creates a hard chromium-carbide layer on the pin surface which increases chain life, at the same time the pins inner core remains soft to absorb the tremendous shock loads without breaking. Highest quality of non O-ring chain in overall combined performance Average Tensile Strength: 8,050lbs.