ILSCO Power Distribution Block, Mechanical connection, Dual Rated, Aluminum material, Tin plated connector,mounting bolt/stud size 1/4 in, mounting hole spacing 4.75 in., UL 1059 Recognized, C22.2 No. 65-03, Copper/Aluminum Primary Conductor 500 kcmil - 4 Str, Copper/Aluminum Secondary Conductor 4/0 Str - 6 Str, 6 conductors, Drive Type Main 3/8 Internal Hex, Drive Type Tap 5/16 Internal Hex, rated for 600 V, primary color Black, 1 poles, 2 ports per pole primary, 4 ports per pole secondary,