Saves The Frame & Your Thumb When Tuning AR-15 Triggers

Drop-in, Delrin block helps you gain a true feeling of trigger movement and pull weight without sacrificing your thumb. Go ahead, drop the hammer; this shock-absorbing block prevents the hammer from striking the wall of the magazine well. Helps eliminate expensive receiver damage and broken hammers. Fits into the magazine well with the upper receiver open or removed, withstands thousands of hammer strikes.