Thomas & Betts 679AL Erickson Coupling. T&B® Erickson Coupling, Threaded, 1-1/2 in, For Use With: Rigid/IMC Conduits, Aluminum, 2-5/8 in OD x 1-31/32 in L. Additional Description: TB -679AL 1 1/2 INCH ALUM ERICKSON CPLG. Catalog Description: 1-1/2 Inch Erickson Coupling, Aluminum, for Use with Rigid/IMC Conduit.