A unidirectional clamping mechanism for clamping a visibility enhancement device such as a strobe light to an aerostat tether subject to deployment and in-haul operation. The clamping mechanism includes diametrically opposed rollers each having a single tooth ratchet and pawl arrangement which allows unlimited rotation in one direction and limited or no rotation in an opposite direction such that when deployed, the strobe lights will not move down the tether but during an in-haul operation the mechanisms may be stacked one on top of the other while the tether is rapidly pulled through them.
