The Manfrotto 160SCK3 Suction Cups with Retractable Spiked Feet (a set of 3) fit upon their "D16" tube, found upon the 190XB, 190XDB, 190XPROB, 190CX3, 190CXPRO3, & 055CXPRO4 tripods.
The suction cups increase the tripod's effective footprint by ~20x,
yielding a significant increase in stability when needed upon certain
surfaces. Retract the rubber cup to reveal a steel tip which provides a
firm footing on soft ground.
These tripod feet can be removed and replaced at will, even in the field