Genuine factory Glock 17 9mm 10-Round magazines. Polyethylene body with a steel liner. Compatible with the reversible mag release on Gen-4 guns as well as earlier Generations 1-3. Fits flush on the full size frames of the G17 and G34, but as with all Glock mags, they will still function in the same caliber compact frame G19, and sub-compact G26.