This is the spacer sleeve originally supplied with the Arca-Swiss quick release, which fits between the locking knob & the edge of the vise grip jaw. It is very practical to carry an extra spacer sleeve and locking knob as insurance; the locking knob can fall off from prolonged vibrations, and the Arca-Swiss quick release is inoperable if either the locking knob or the spacer sleeve are lost or damaged from impact.
