Thomas & Betts 144 Conduit Locknut Brand: Thomas & Betts. Part Number: 144. T&B Conduit Locknut, 1-1/4 in, For Use With: Rigid/IMC Conduits, Steel, 2-5/32 in H x 13/64 in THK. Additional Description: TB -144 1.25 INCH STEEL LOCKNUT. Catalog Description: 1-1/4 Inch Steel Locknut for Use With Rigid/IMC Conduit..