A super wide lens with M67 thread.
Fits many housings - particularly the Olympus TG cameras (TG-4 and TG-5) - just remember to add the M52/M67 converter.
It is a dual use (land/underwater) wide conversion lens specially designed for 28mm wide camera (35mm film equivalent). The maximum view angle is 100.8 underwater for wide imaging and 179 on land for fish-eye imaging. Unique optical design allows to shorten minimum focal distance with ultra wide view angle thus effective for wide macro shot.
If you use the optional "Dome Lens Unit II for UWL-H100" it further increases maximum view angle to 144.8 underwater for semi-fisheye imaging.