Eaton Weatherhead 1344 Air Brake Tubing Bulkhead Coupling, 1/4" Female Pipe Thread (Pack of 4) Bulkhead coupling for joining lengths of copper air brake tubing through a barrier in air brake systems 1/4" female NPT threads on each end for connecting copper air brake tubing, and 3/4-16 SAE outer threads for threading the fitting into a hole CA360 brass for strength and resistance to corrosion Operating temperature range of -65 to +250 degrees F (-53 to +121 degrees C)