We cannot say if this latest ACM airsoft pistol available at Airsoft Panda is compatible with some existing Walther PPK/S pistols made elsewhere. But this one is a full metal CO2 powered airsoft pistol which you can get for US$65.00. This is fully marked which you can see in the photo below, no FPS out of the box mentioned so if you get one better check it out immediately if it can be used for skirmishes or just plain target shooting according to your local laws.