5 dptp - flat lens 38mm can be rotated to any position with finger screws - power and base are marked on prism - small model comes with a thicker elastic band that has Velcro attachment for easy on/off [Full description below...]
Description
5 dptp - flat lens 38mm can be rotated to any position with finger screws - power and base are marked on prism - small model comes with a thicker elastic band that has Velcro attachment for easy on/off