Crafted from durable crack-proof polymer and reinforced with full-length steel inserts Glock factory mags feature numbered witness holes and a branded baseplate. This 10-round full-sized magazine is compatible with Glock G31 G32 & G33 Pistols. Perfect for training or target practice. Body : Polymer with steel insert Base pad : PolymerMagazine loader recommended to ease the loading processNOTE: GLOCK MAGAZINES CAN BE VERY DIFFICULT TO LOAD WHEN NEW. OFTEN THE LAST ROUND WILL NOT FIT UNTIL THE MAGAZINE HAS UNDERGONE A BREAK-IN PERIOD. IT IS RECOMMENDED THAT THE MAGAZINE BE LOADED WITH ALL BUT THE LAST ROUND AND LEFT FOR A FEW DAYS TO COMPRESS THE SPRING. CYCLING THE MAGAZINE FROM FULL TO EMPTY MULTIPLE TIMES CAN ASSIST IN THE BREAK-IN PERIOD.