1/4" Male NPT threaded 15 PSI air compressor/tank pressure safety relief valve. Also known as a "Pop Off" or "Blow Off" valve. This relief valve is manufactured in the United States. The relief pressure of this valve is set at 15 PSI and is accurate within + or - 3% of the set pressure. 

Specifications:

• Pressure Setting: 15 Psi
• Valve Inlet Threads: 1/4" Male NPT (measure about 1/2" in diameter) 
• Total Valve Length: 1-3/4" 
• Features a viton soft seat relief valve to prevent leaks even in high-temperature applications
• Max temperature: 250° F 
• Solid Brass Construction
• Made in the U.S.A
• Manufactured by Conrader