This replacement or spare magazine is compatible with your GSG-5. It is constructed of DuPont Zytel polymer with injection molded mag follower and mag spring formed from chrome silicone wire. Made in the USA.
Specifications:

Caliber	22 LR
Capacity	22
Finish	Black
Model	GSG-522/GSG-5
Material	Polymer
Type	Detachable
Model Fit	GSG-522/GSG-5
Brand Fit	GSG
Max Capacity	22