The eye (E-10) flip cap features three detent positions that allows the shooter to have the cap stand straight up (Pos. 1) to access custom laser engraved dope disk (optional accessory-sold separately from Vortex) data with ease. The second and third positions allow for 45 degree and 90 degree lay flat positions. A high quality flat spring and robust hinge design ensure barrier free vision and reliable operation, every time. Eyepiece fits all Vortex Riflescopes excluding Viper 1” tube