Hyperco's B-Series Coil-Over Spring — 2.5" ID, wound from high-tensile chrome silicon wire, ±2% rate tolerance. A NASCAR Cup Series supplier. The most precisely rated 2.5" coil-over spring available for dirt Late Model racing — the rate you order is the rate you get, every time. 2.5" ID — fits standard Late Model coil-over hardware Available in 4", 5", 6", 7", 8", 9", 10", 12", 14", and 16" lengths Rates: 85–1000 lb/in — full working range for every Late Model corner position ±2% rate tolerance — tightest available High-tensile chrome silicon wire — won't take a set Dark blue powder coat — easy ID at a glance Select your length and rate below. Not sure what to run? Area 51 can help you build the right spring combo for your car and track.