Straight-threaded Adapters, for adapting hose/tubing through a panel or bulkhead. These fittings have either a 1/4-18NPSM or 1/4-28UNF thread, and come with an accompanying hex nut. Optional Red Silicone or Buna-N Washer available (1/4-18NPSM thread only). If you don't see the part you are looking for, just Contact Us. Many fittings may be available in alternate sizes and materials.