Thomas & Betts 146-TB Conduit Locknut Brand: Thomas & Betts. Part Number: 146-TB. T&B Conduit Locknut, 2 in, For Use With: Rigid/IMC Conduits, Steel, 3 in H x 7/32 in THK. Additional Description: TB -146-TB 2 INCH LOCKNUT STL RIGID/IMC. Catalog Description: 2 Inch Steel Locknut for Use With Rigid/IMC Conduit..