The Trinity Force H2 SBA Recoil Spring is a drop-in buffer system designed to help the AR-15 platform function more smoothly and quieter. The H2 style buffer weight system is an all-in-one system with higher tension and more reciprocating mass than the standard SBA. It is easy to install and quickly reduces friction and vibration with much smoother harmonics than traditional buffer systems. Fits M4-style buffer tubes for AR-15 semi-automatic rifles. Fits M4-style buffer tubes for AR-15 semi-automatic rifles. All-in-one system High strength aluminum and steel Smoother harmonics Easy install/ No gunsmith needed