Extra heavy duty tin-plated copper lugs are designed with thicker walls for greater strength and conductivity and have been identified for use in severe-duty applications. The product has the gauge size stamped on the lug for easy identification. Each lug can be crimped or soldered and has a stackable construction that offers maximum conductivity and flexibility. This 4/0 gauge, 5/16\" stud hole, copper lug is a great replacement product for old or damaged battery cable ends.