The BD Micro-Fine + needle is 8mm (5/16 ") long and 31G thick. It is one of the thinnest needles available. Consult your doctor before switching to a shorter needle. Needles should not be used more than once. Currently insulin needles are thinner and of high quality to ensure greater comfort, so re-use may damage the tip of the needle causing skin damage. For your safety you should NOT use needles more than once. Size: 0.25 mm x 8 mm, Weight: 31 gr. Content: 100 units