This is a dual coil spring with damper measuring 1.437" outside diameter and .630 ID. The seat pressure is 140lbs at an installed height of 1.750" and open pressure is 335lbs at 1.150". Max lift is .625". This spring works great for our ZZ9x, ZZ10, ZZ409, and ZZx line of camshafts. Choose our 6.SPS500 spring seats and our 6.RET500 steel retainer for the low-cost option or our 6.RET505 Titanium retainer for optimum high rpm performance. Sold as a set of 16.