Connects 2-pieces of a threaded rigid conduit when one piece of the conduit cannot be turned. Ideal fitting for retrofits. Key factors for 3-piece couplings alignment, consistent centerlines, strong threads. Since it is 3 individual components the weight of the fitting should be considered. Malleable fittings are bulky and are 2 to 3X the weight of steel. Due to its low brinnel hardness ratings, die-cast has been known to deform under stress load and the softness of the threads will loosen over tight.