* Add the suffix"V" to the part number to specify vinyl ester Example"WR500V" * Add the suffix"-SQ" to the part number to specify square washer Example"WR500-SQ" Aickinstrut All-Thread Washers are flat fiberglass wshers for use with FRP all-thread rods. All-Thread rod washers are 1/4" thick with a 17/8" diameter and are available in polyester or vinyl ester resin. To order vinyl ester, add the suffix"V" to the part number. To order square washers add the suffix"-SQ" to the part number.