This connector is a black, 600 kcmil with a length of 4.120 in (104,6 mm), a 0.923 in (23,4 mm) I.D. and a 1.430 in (36,3 mm) O.D.
The 3M™ Scotchlok™ Aluminum Connector 20016 is for use with copper or aluminum conductors. These aluminum connectors feature color coded end caps for identification. Contact aid provided in connector barrel is compatible with poly/EPR insulations.
Scotchlok Aluminum Compression Connectors - Data Sheet (PDF 37.2 K)