The Manfrotto 116SPK3 Retractable Spiked Foot Set (3 Pieces)
is an optional upgrade made to fit their "D16" tube, found upon the
190XB, 190XDB, 190XPROB, 190CX3, 190CXPRO3, & 055CXPRO4 tripods.
The broad, tough spikes are made from a hard-wearing anodized
aluminum alloy, and will significantly increase stability on soft earth
surfaces. Each spike's surrounded by a retractable hard rubber foot,
with tapered concentric circular rubber ridges that get smaller as they
approach the ground surface.
These tripod feet can be removed and replaced at will, even in the field.