Langdon Tactical Technology SCDG5 Striker Control Device (SCD) for Glock

The Striker Control Device (SCD) is a cover plate for your Glock pistol that blocks the rearward motion of the striker when thumb pressure is applied to the back of the slide - similar to a hammer on a DA/SA hammer fired pistol. It was originally developed by Tom Jones and Todd Louis Green from the inspiration of double action hammer fired pistols, where shooters are taught to keep their thumb on the hammer when holstering. Keeping your thumb on the back of the hammer gives you positive feedback should something be caught in the trigger guard to prevent the gun from firing. The SCD does just that for the Glock striker fired pistols.