The ZEV Technologies Competition trigger spring is 28% heavier than stock and provides additional force to assist the operator in pulling the trigger while providing for a more positive reset. Reduces trigger pull weight by up to 1 lb. NoteFits all Glock Gen 1-4 Models except Glock 42 and 43 DISCLAIMER: This product is not manufactured, authorized, endorsed, or warranted by GLOCK. GLOCK does not warrant or represent that this product is compatible with GLOCK pistols.