Puko II Retro Ring Stretcher 

It is used both to enlarge and reduce rings as well as to roll up rails on rings or bend rails of different cross-sections and max. thickness up to 4 mm in the shape of an arc of a selected radius. The enlargement (from the diameter of 13 mm) takes place after the ring is placed on the conical sleeve of the device, which expands under the pressure of a manual lever. The wedding ring is reduced by pressing it into the appropriate conical or spherical hole of the profile by means of a punch. Thanks to the precisely matched sleeve segments, the gentle angle of the sleeve cone and the perfectly polished surfaces of both the extension sleeve and the reduction holes, the rings do not change their circular shape or leave any marks on them. The working surface of the sleeve is covered with a special chromium layer, which makes the device more durable. The eccentric transmission mechanism allows the rings to be reduced and stretched with little effort even from very hard alloys, e.g. platinum.