This combination Needle Guide and Magnifier was designed to make reading markings on a syringe easier with up to 1.7 times magnification and to help guide the syringe needle into a vial. Works with BD 1CC, 1/2 cc and 3/10 cc insulin syringes. It's easy to use... Simply nest the vial in the semi-circle guide at the end of the magnifying bar and from the other end, slide the syringe along the channel guide and into the vial. You'll be able to see and measure the correct doses more easily and accurately than ever. Measures 3-1/8 Long x 7/8 Wide x ¾ Thick.