40 S&W
 
The 40 S&W caliber closes the gap between the heavy 45 Auto calibers and the 9 mm Luger service calibers. GLOCK was the first manufacturer to make the advantages of this balanced caliber accessible to law enforcement agencies. By applying the Gen4 technology with the Modular back strap design and the reversible magazine catch to this pistol model the user may instantly customize its grip.