Suck-back metering valves are designed for use with medium to high viscosity materials such as oils, greases, silicones, etc. Closing the valve creates instant material shut-off and suction of residues, thus ensuring clean metering. The valve can also be supplied with air to a second port to close the valve, thus ensuring accurate material metering. Dose volumes can be adjusted by turning the knob at the top of the valve. Poppet valves are excellent for applications larger than 2 mm wide.