Insulin Pen Needles Ultra-Fine 31 gauge x 5mm (100/box) BD 320119The BD Ultra Fine Mini pen needle is 31 gauge, 5 mm (3 16"). It's the shortest insulin pen needle in the world, and no insulin pen needle is thinner. It can be safely used by both children and adults, providing reliable injections with no "pinch up" of skin required. You should consult with a health care professional before switching to a shorter insulin pen needle. Today's insulin needle is thinner and more delicate for greater comfort, so needle