Available in variety of sizes, these respiratory valves or check valves are used for supporting respiratory circuits. Since these are uni-directional, they allow the flow of gases in only one direction. They comprise a spiral type diaphragm which is sensitive to the low flow and is highly elastic and gravity independent. Besides, the device has two similar sized ports where the outer port is transparent and permits the view of diaphragm. The valves are selected according to the size of the subject and the flow of resistance required. Constructed from autoclave material, these have a hose barb for sampling of gas. Also, it is connected with straight medical tapers and standard medical tapers which allows quick and hassle free attachment of the valve to other components.