Abstract: A mechanism for secure engagement of slideable elements in dovetail or similar tracks. The mechanism comprises a pair of plate-like clamping elements adapted to be received within a slide track. The plates are disposed in non-engaging face-to-face relation having a spacer element positioned therebetween adjacent lower edges of the plates. The lower edges project outwardly in relation to the spacer at an angle to engage interior sidewalls of a slide track. A lever element is adapted to converge the upper portions of the plates in a direction towards the spacer and thereby force the lower edges securely against the slide track. The spacer element can be rotatably mounted and can have a non-circular cross section to facilitate installation and removal of the mechanism.