Catheter Set in Case The wooden case box consists of a hinged lid, secured with two push-fit locking mechanisms. Upon opening, the case reveals 12 different-sized metal catheters, each composed of a hollow and curved shaft, with two lateral oval fenestrations towards the blunt closed tip, and the other end with two finger rings. Inside each catheter, there is a cleaning wire ending with a finger ring. On the finger-ring tip, there is an embossed number indicating the size of the catheter, ranging from 12 to 1. 1925-1975