The Q-Series Magazine Carriers are built with extreme durability to perform exactly how you want. It's an ambidextrous, low-profile and concealable design that can be worn with or without a belt. A positive rentention on both magazine and the waistline keeps everything right where you want. This magazine carrier fits the Glock 42/43 and M&P Shield magazines in .380, 9mm, and .40 cal. The Mag Carrier is not compatible with .45 cal.