The Tubb SpeedLock flat wire spring is heat-treated, stress relieved and shot peened to increase reliability and service life. Spring fits both carbine and standard length stocks. FeaturesBolt load is increased by 10% compared with Tubb round wire buffer springsProvides a flatter recoil impulseRequires about 6% less force to fully compress than Tubb round wire buffer springsLess than 2% change in spring loading through 500,000 compression cyclesDuty rated for 1,000,000 cycles