This connector is a green, 4 AWG with a length of 1.880 in (47,8 mm), a 0.265 in (6,7 mm) I.D. and a 0.486 in (11,8 mm) O.D.
The 3M™ Scotchlok™ Aluminum Connector 20002 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)