3M Scotchlok copper compression lugs are one piece, seamless copper and are designed to cover a wide-range of conductor sizes, they are available in one hole, standard barrel and one hole and two hole long barrel versions, the 31000 series consists of one hole, long barrel length lugs designed to cover conductor sizes from 2/0 AWG through 600 kcmil (MCM) and, two hole, long barrel length lugs designed to cover conductor sizes from 2/0 AWG through 1000 kcmil (MCM).