1/8" 1/4" 3/8" 1/2" BSP male-to-female pneumatic check valve Full-way check valve for air, water, oil and natural gas
https://www.vogueparade.com/shopping/EN/200282142/1/10000401955551/18-14-38-12-bsp-male-to-female-pneumatic-check-valve-full-way-check-valve-for-air-water-oil-and-natural-gas//