This charger plugs into the silver disk marked "Battery Charger" in your RBTIV carrying case. The charger should be connected only when your RBTIV needs to be charged. It should not be plugged in all the time as this will damage your battery. An overnight charge is recommended as needed.
A quick seating one way check valve is specifically designed to reduce the likelihood that a subject can suck back through the mouthpiece while submitting a sample. This mouthpiece is designed in a manner that it actuates the power up circuit on the Alco Sensor IV. Its design also facilitates the automatic ejection of the mouthpiece for hands free removal at the end of the test.