Closed Spelter Sockets. Forged Steel Sockets thru 1-1/2″, cast alloy steel 1-5/8″. thru 4″. Spelter socket terminations have an efficiency rating of 100%, based on the catalog strength of wire rope. Ratings are based on the rmended use with 6 x 7, 6 x 19 or 6 x 37, IPS or XIP (EIP) , XXIP (EEIP), RRL, FC or IWRC wire rope.