These fittings, less the EMT connectors and conduit nipple, are our Type AX expansion fittings which are listed by Underwriters Laboratories, Inc., for use with rigid conduit when used with bonding jumpers
Concretetight
O‑Z/Gedney TX expansion fittings allow for expansion and contraction in a run of electrical metallic tubing (EMT). They provide for a maximum of 4" conduit movement, 2" in either direction.