The CKV-M3 valve is commonly used for gas and pneumatic applications, and is said to be useful for applications that cannot tolerate any leaks or back flow. It can be appropriate where space, weight, and sealing reliability are critical. Maximum length is about 0.75 in. and the body is made from 5-mm hexagonal stock. The valve weighs just above 2 gm in brass and 303-stainless steel. The valve incorporates an elastomeric duckbill within its design that allows it to withstand up to 250-psig backpressure. It cracks open to allow flow at as little as 0.5 psig. This check valve is available with an in-line barb-to-barb configuration, internal or external M3 threads and any combination of the three. Optional seal materials are available such as silicone, fluorocarbon, and EPDM.