Genuine Omega case opening tool. For the serious watch enthusiast or the man who has everything! Internal diameter 20.5mm. Will engage with cases that have 6 tool recess points and helps ensure the case is opened without damage. Sadly so many cases have been scratched and damaged by ham-fisted individuals trying to open a screw case using just one recess point and a screwdriver! This is marked (size number) 2, Omega with the Omega sign within the familiar triangle and then Swiss made, fab suisse, model depose. Wonderful patina.