Becton Dickinson Ultra-Fine III Mini Pen Needle the shortest, thinnest pen needle in the world can be used safely 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 pen needle. Paper tab and inner shield are color-coded purple for easy size/gauge recognition. Fits all pens and dosers. 31 g x 3/16".