Our BHUDC Series Bulkheads are Manufactured in house by Pneuline Supply, Inc. and offer a unique flatted side to fit a Greenlee D punch: excepted 3/8 barb, thus avoiding the possibility for the Bulkhead to turn. Bulkheads are assigned sizes from the outside of the panel to the inside. Available in 1/8 inch, 1/4 inch, and 3/8 and ½ inch sizes, or any combination: exception ½ is standard In and out. Materials available are Natural Nylon, Polypropylene, PVDF, and Acetal. All products are gamma sterilizable. Zinc-plated nuts are available for Nylon bulkheads, and Nylon nuts are available for all other bulkheads.