Wilson Combat Anti-Walk Hammer, Trigger Pins replace your AR trigger and hammer pins to ensure pins do not rotate or vibrate loose out of the receiver. This is a popular, inexpensive and drop-in enhancement for tactical, hard-use guns and full auto firearms. These pins are compatible with a standard USGI style AR style lower receiver with standard GI trigger pins of .154" diameter regardless of caliber, including 7.62/.308 length AR receivers. FeaturesAnti-walk/rotationFits standard USGI .154" diameter pin receivers