This connector is a red, 250 kcmil with a length of 2.940 in (74,7 mm), a 0.594 in (15,1 mm) I.D. and a 0.906 in (23,0 mm) O.D.
The 3M™ Scotchlok™ Aluminum Connector 20009 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)