This is a 0.63 in (16 mm) O.D., transition connector from cable A (4 AWG Stranded, 2 AWG Solid) to cable B (1/0 AWG Stranded, - AWG Solid). This is used with 3M™ 5411 and 3M™ 5501 splice kits.
3M CI Series Connectors up to 35kV - Product Selection Guide (PDF 8.0 K)
3M CI-A Series Connectors up to 35kV - Product Selection Guide (PDF 6.6 K)
3M CI-T Series Connectors up to 35 kV - Product Selection Guide (PDF 7.0 K)
3M™ Lugs and Connectors, 2015 Electrical Products Catalog - Catalog (PDF 2.1 MB)
3M™ Splices, 2013 Electrical Products Catalog - Catalog (PDF 11.7 MB)