Magazine Base Interchange System. Machined 7075-T6 aircraft aluminum construction with a flat, non-reflective type 3 hard coat anodization. Mini tactical rail is designed with the intention of a quick attachment system for accessories in military, law enforcement and home security applications. Allows the user to pre-connect an accessory to the rail and attach on the fly with a simple click. Fits all Glock 9mm/.40 except G26 & G27.