Polaris IPLD 500-4 Cable Connector Multitap - Black 500MCM-4AWG.
Multi-tap Connector, #4 AWG -500MCM conductor sizes. Insulated, Plastisol insulation material.
-45C to 90C operating temperature. 
600V
5.24 overall length
Part is not in original packaging, but is unused and in pristine condition.