Keyes Cutaneous Punch, Sklar. 4 in., 2mm, Straight, Round, Stainless Steel. Sklar's Keyes Cutaneous Punch is a dermal diagnostic instrument used to remove skin samples for biopsy. The round sharp end is pushed into the skin and twisted slightly to cut away a small plug of skin. The solid knurled handle provides a gripping surface for the user who controls the depth of the excision. The Keyes punch is often used in gynecological biopsies where a deeper tissue sample is useful for the pathologist. This specific punch has a 2mm diameter, however, is available up to 8mm.