The Safariland 578 pro fit for the Glock 17/22 9mm/.40S&W semi auto handguns is a masterpiece of engineering. Made from the excellent SafariSeven material which provides unparalleled durability, weather and temperature resistance. The model 578 pro fit Glock 17/22 utilizes the excellent GLS or Grip Lock System allows the firearm to be locked into place when holstered for added security for a law enforcement off duty carry or concealed carry holders who prefer extra retention. The best part about the GLS retention system is that the release is activated by your middle finger with a natural grip. Due to the construction of the Safariland 578 pro fit and the GLS system it is designed to fit over 175 different firearms safely, simply use the supplied tools to adjust the holster to fit your specific handgun. For all day carry comfort, Safariland 587 GLS pro fit for the Glock 17/22 comes with an injection molded paddle attachement and ambidextrous belt loop attachment for a little left handed friendliness. This 578 pro fit is for a left handed shooter.