Q:  What do P7 K3 .22LR style magazines look like?

A:  P7 K3 .22LR magazines are designed to only be used in the P7 K3 pistol.  They hold 10 rounds of ammo.  Here are the  magazines:

p7k3_22LR_R.jpg (563710 bytes) p7k3_22LR_L.jpg (644416 bytes) p7k3_22LR_3.jpg (206765 bytes)

Q:  Are there aftermarket P7 K3 magazines available?

No, not to my knowledge.