Designed to make a leak-tight seal without the use of O-Rings. Simply tighten until white ring appears indicating a seal has been made, then secure locknut. No need to over-tighten. Ace-Thred adapters feature a 1/4-28unf tap, with or without a 18-8 stainless Helicoil insert for durability. See our glass column product families, 5795 and 5820, our 5854 1/4-28unf tap tubing connectors, our 5814 and 5848 packing supports and our 12684 PTFE tubing.