The RGU-FM is an East German oxygen rebreather of world-renown East German quality. It is a uncertain mass flow SCR. Excellent description of the rig is at Diver Dave's Tear-down pages. Check it out. Golem Rebreathers acquired this rig to conduct currently classified experiments and modificatons.

RGU-FM was tested with the original scrubber material (date of manufacture 1979) and original oxygen fill (1975) at EDL/CzN fresh-water test facility in northern Florida, formerly known as Ginnie Springs.