BD Ultra-Fine Pen Needles 4MM 32G:Insulin is meant to be injected into the fat layer just below the skin for consistent absorption. If you inject into a muscle, the insulin can work too quickly, which may lead to low blood sugar. The BD Nano™4mm Pen Needle, BD’s shortest pen needle gets insulin to the fat layer over 99.5% of the time, at all injection sites.Key benefits:BD's smallest, thinnest pen needle.EasyflowTM technology for less effort to injection.PentaPointTM Comfort for a smoother, gentler injection experience.