The AMPTEC 620A-4 Fail-Safe Ohmmeter (and the AMPTEC 620A4R Water Resistant version) is a portable, battery powered 4 ½ digit DC Ohmmeter that safely measures electrical resistance for use on a variety of potentially hazardous devices. It has been specifically designed to test squibs, igniters, flares, airbags, explosive bolts, etc.