Reliability of our ETS mags: The ETS transparent Glock mags take visibility and safety to new level. Users are able to quickly determine the round count and ammo type from any viewing angle. These mags have been through rigorous testing including several 1000s of rounds ran through them without failure, using all generations and size of Glock pistols. Several different brands of ammo was used in testing, including hollow points. We cut no corners in testing to insure our mags deliver the same reliability that is expected out of OEM Glock mags. The ETS GLock mag: Fully compatible with aftermarket base plates. Reliably hold the slide back when empty. Mfg: Elite Tactical Systems Group