BULKHEAD UNION/NYLON/ Tube to Tube, 3/8 inch tube outside diameter. 282N06NYLO-Seal Bulkhead Union | Fits 3/8in TubingNYLO-Seal Nylon Bulkhead Unions have excellent resistance to acids, alkalis, dilute mineral acids, most organic acids, petroleum oils and greases, and photographic solutions. Install..