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.