Strike Industries Locking Block Pin for Timney Alpha Trigger Glock Gen3 and Gen4 Black. When using Timney Alpha Triggers in Glocks there is a trigger return spring that the mechanism relies on in order to reset the trigger. Unlike the OEM trigger housing Timney's system relocates the trigger reset action towards the front of the frame rather than in the rear. Normally this return spring rests on the locking block pin but it can move around as the return spring is unrestrained. With the Strike Glock Locking Pin upgrade there's a groove which is used to retain the return spring in a vertical position. This reduces spring binding and wear to the safety shoe creating a more consistent and smoother shooting experience with each press of the trigger further improving upon the competitive nature of Timney Alpha triggers for Glocks. Specifications for Strike Industries Locking Block Pin for Timney Alpha Trigger: Manufacturer: Strike Industries Color: Black Gun Make: Glock Model Generation: 4 3 Features of Strike Industries Locking Block Pin for Timney Alpha Trigger Smoother trigger movement For Timney Alpha Competition Triggers for Glock Gen 34 Retains return spring in vertical position Reduces spring binding and wear to safety shoe Package Contents: Strike Industries Locking Block Pin for Timney Alpha Trigger Strike Industries SI-G-LBP-T-G3N4: Locking Block Pin for Timney Alpha Trigger Glock Gen3 and Gen4 Black