The Phone Skope's Universal Optical Adapter is one of two required pieces. This adapter comes in two different sizes, the U-1 mini and the U-2. These adapters lock into the Phone Skope Phone Case, which is sold separately. With the ratchet-style locking mechanism, this adapter will adjust to create a solid mount to most optics.
Attaches phone to optic
U-2 Size: 1.7 in. to 2.34 in. eyepiece diameter
U-1 Mini Size: 1.2 in. to 1.9 in. eyepiece diameter