Thermo Scientific™ Nalgene™ Vacuum Check Valve and Pressure Connector is compatible with tubing with ID ranging from 1/4 in. (6.35mm) to 5/16 in. (7.94mm), and works best between 10- and 28- in. Hg. Nalgene™ Vacuum Check Valve and Pressure Connector is used in conjunction with aspirator-type vacuum pumps and can prevent back pressure.