AKA: 21KS. Status: tested 1990. Gross mass: 218 kg (480 lb).
The UMK weighed 218 kg. In case of a malfunction, it remained connected by a tether attached to a winch on an EVA mast installed near the Kvant-2 exit hatch of Mir. The UMK was used on only two EVA's, at distances of up to 45 m from the station. Unlike the shuttle MMU, it was only flown tethered to the station. Like the shuttle MMU, it was retired after a few tests.