BD Ultra-Fine Short Pen Needles 8mm x 31G, 100/boxBD 320109 Ultra Fine Short Pen Needles 8mm x 31G are made specially to help alleviate the discomforts associated with injecting most injectable drugs, such as insulin. These Pen Needles create a smoother dosage which can help reduce skin puncture stinging. Furthermore, their ultra fine construction helps users inject accurately, easily and swiftly. As such, they are particularly suited for young, elderly and overweight users of insulin injections.