Well, not EXACTLY one type of medal, but I think safe to say - postwar no doubt, typically aluminum with appointments of lesser quality/cheaper materials in general. Interestingly, you do find specimens with both the very simple non-safety pin attachment device, as well as the safety pin type (one you have shown) and this one in my collection - perhaps from a time when the safety pin attachment was reintroduced, represnting a somewhat later piece? That, or there were different makers, some of which used safety pins, some of which used the non-safety type across the same time periods, but I do not subscribe to this "theory" myself.