Abstract: The invention comprises an apparatus for connecting two elongate members (16, 10) in parallelism and so that one may be moved relative to the other, the other member (10) being adapted to be rigidly mounted and having a neck portion (12a) extending longitudinally and terminating laterally in a longitudinal bead (11) engageable in a longitudinal groove (22) of a longitudinal edge flange of the one movable member (16), there being provided an anti-friction contact strip (17) between the members (16, 10), the strip (17) being substantially tubular or arcuate in cross-section with a longitudinal slit (28) through which the neck portion (12a) of the other member (10) extends when the two members are connected, the parts being so made and arranged that the strip (17) may be fitted by end-wise longitudinal sliding into and along the groove (22) and about and along the bead (11), and the two elongate members (16, 10) and interposed contact strip (17) are then restrained against separation by forces applied transverse