Holt’s instrument consists of two blades, joined at the vesical extremity.  Each blade has a handle, these are kept in place by a brace provided with a set-screw.  A conducting rod runs from the point-inside of the blades- and projects just outside the handles.  Four different sizes of tubes fit upon the rod between the handles that serves as a guide to keep the tubes centered within the two blades. An exceptional example by Lollini with horn handles, cased, EC.