These flat wire, high-quality action/buffer springs from champion shooter David Tubb will perform flawlessly and are duty rated for 500,000 compression cycles at maximum performance. Made to “extra power” specs without the extra material, these springs are surprisingly lightweight, yet exttremely durable. Gives correct timing and resistance on the recoil stroke and a controlled rebound ensures reliable feeding with consistent forward thrust on every shot. Keeps the bolt locked a little longer to allow pressures more time to subside for perfect cycling. Mfg: Superior Shooting SPECS: Chrome silicon steel. AR-15 fits both fixed and collapsible stocked AR-15 rifles and carbines without modification to spring or gun. AR-10 .308-style fits both AR-10 and SR-25/LR-308 platform Rifles and Carbines with either rifle or carbine receiver extensions.