Water heater 600 psi Safety Pressure Relief Valve 1/4"

Water flow direction is from Male pipe to female pipe.
Both connections are 1/4" national pipe
Brass body with a Stainless male nipple.
Install between the heater and outbound water connection.  
Designed to protect the heater in the event the water expanse too rapidly.

Used on 90% of all portable carpet cleaning machines that have heaters on them.
Other pressures available.

Also sold under part Mytee B118
Also used on many Sandia Plastics and Clean Storm Extractors. 
Bane-Clene 25016