Infantry fortress K-S5 U potoka
Infantry bunker KS 5 ( where K = Kralíky section of fortifications, S = Infantry bunker and 5 = serial number of the building in the fortification line ) with the code name " U potoka " is a typical representative of heavy fortification ( TO ), which was to secure the northern border of Czechoslovakia against sudden invasion of the German army, to enable the undisturbed mobilization of the field army and possibly also to protect its flank during a possible retreat ( under the pressure of a stronger adversary ) towards Slovakia.