Apex Tactical Specialties Ultimate Safety Plunger For Glock, Stainless Steel 102-102 The Apex Ultimate Safety Plunger for Glock is designed for use in the Gen 3 and Gen 4 Glock 9mm" .40 S&W" .357 Sig caliber pistols and will smooth out the trigger take-up when compared to the original factory component. The Ultimate Safety Plunger maintains proper safety function.