Larger Reducing Bushings Zinc die-cast 2-1/2in x 1-1/4in to 4in x 3-1/2inDescription Larger Reducing Bushings Zinc die Reducing bushings, unlike reducing washers, maintain grounding path and are able to pass UL high current testing. These Bushings are made of zinc die cast and are available in multiple dimensions. Specifications Part Number Trade Size Dim A Dim B Dim C NPNB 1274 2 1 2" x 1 1 4" 7. 5 3. 5 5. 25 NPNB 1275 2 1 2" x 1 1 2" 7. 5 3. 5 5. 25 NPNB 1276 2 1 2" x 2" 7. 5 3. 5 5. 25 NPNB 1283 3" x 1" 10 4. 0625 6.