Cork Borers Set of 6. Nickel plated brass with rod Inside.  Bore Sizes as follows:  8.45mm, 7.5mm, 6.3mm, 4.9mm, 4.0mm, 3.4mm. Used to cut hole in cork or rubber stopper to insert glass tubing. Also used to take samples for experiments and punch holes on an agar plate. Overall length: 100mm