5 different stainless steel adapters to choose from. 1. 1/4" MNPT? to 1/8" Barbed fitting , barbed end is .06" I.D. maker unknown The threads are not tapered. O.D. of threads is .495" for the full length, I.D. of threads is .473", appears to be about 20 TPI 2. 1/2" Tri clamp to 1/8" Barbed fitting not EAGLE maker unknown 3. 1/2" Tri clamp to 1/4" Barbed fitting EAGLE brand USA 316L 4. 1/2" Tri clamp to 3/8" Barbed fitting EAGLE brand USA 316L 5. 1/2" Tri clamp to 1/2" Butt Weld  ASME BPE 316L very smooth finish I.D.