FLIR Tau WFOV Lens Locking Ring
The lens locking ring is designed to mount a Tau WFOV camera into a bulkhead. The M29 x 1.0 thread on the outside of the lens mount flange is placed through the clearance hole in the bulkhead and the O-ring seals the camera to the face.
The Type 2-025 O-ring is not for sale through FLIR. This is a standard O-ring available from many suppliers.