Thomas & Betts RE21-TB Reducing Bushing Brand: Thomas & Betts. Part Number: RE21-TB. T&B Reducing Bushing, Explosionproof, 3/4 to 1/2 in, Steel, Zinc Plated. Additional Description: TB -RE21-TB 3/4 IN -.5 IN, REDUCING BUSHING, XP BUSHING,. Catalog Description: 3/4 Inch to 1/2 Inch Reducing Bushing, Steel Zinc Plated..