Diop MWIR 3-5um 1x IR Microscope f3.0 objective lens. Bayonet mount - fits such cameras as Amber Radiance, Indigo Merlin MWIR and Phoenix, Santa Barbara Focal Plane, IRCameras and so on. Widely used mount. If not sure - ask me before bidding. 83mm focusing working distance from lens front according to datasheet (I measured 92mm). In the last picture - camera sensor is 256x256 30um - ruler 0.3" fits side - this is exactly 1X. No barrel distortion - as you can see. There is no focusing ring - lens is fixed - move camera or target instead. 1X magnification - not a lot for "microscope" - but could be useful in some situations - like you try to figure out mystery sensor in your new vintage thermal camera - you can shoot video with your other thermal camera - as your sensor-in-question starts cooling down and wires become distinct for a moment. This particular lens has built-in filter wheel. There are retaining rings but no filters. Comes with front cap.