This kit contains two replacement Shok-Buffs and one heavy-duty recoil spring. Two of the most effective and inexpensive ways to maximize your 1911's long life and accuracy are to use Shok-Buffs and quality recoil springs. Theses drop-in parts help eliminate the battering of critical components. To ensure maximum protection, recoil buffers should be replaced every 1,000 rounds and recoil springs every 2,000 rounds. Includes 20 Pound heavy recoil spring and 2 Buffers.