The sensor meets the new SAE J2791 standard and doesn't touch refrigerant as it passes through the instrument.
The 22791 is compact enough to fit in a hand and has a ruggedized construction which stands up to abuse. It also has an 8-hour battery life as well as mute and peak functions. A magnetic hanger helps keep the detector out of the way when repairing a leak, but visible so that it is not left on the job.
More info: www.robinair.com