This listing is for a brand new set of Z28 +.100" style performance valve springs that are made by Elgin Industries. Set includes 16 springs. The Z28 +.100" springs are stock outside diameter and can be used in many 1955-1993 small block Chevy V8 cast iron cylinder heads. They work great for stock, towing and most mild performance cams and work best with cams up to 0.550" lift. SPECS: Outside Diameter: 1.260" Inside Diameter: 0.785" Closed: 125 lbs. @ 1.750" Open: 325 lbs. @ 1.200" Coil Bind @: 1.160" Spring Type: Single spring with damper.