The bevel of the piercing needle is its cutting edge. It is made by a flat angled grind across a piece of surgical tubing. A tri-bevel needle involves three different cuts at slightly different angles. A bevel needs to be long enough so that it cuts and lifts the tissue rather than coring it out like a dermal punch. In addition, the rear angle of the bevel needs to be such that the back half of the bevel does not "catch" the skin as it enters the body.