The Tracerline TP-9363 PRO-Chek CG combustible gas leak detector is a diagnostic tool for finding leaks in compressed natural gas vehicles, acetylene welding tanks and propane tanks. It detects gasoline, methanol, ethanol, methane, ethane, butane and other toxic gases. The PRO-Chek CG features a three-position switch with a sensitivity slide that helps pinpoint the location of each leak. Additional features include a variable auto alarm and flashing yellow LED to determine the size of the leak and an auto-zero function that blocks out background gas levels. The detector’s chrome-plated, flexible metal probe holds its position in tight areas, the company says. The product comes with sensor, two D batteries and a carrying case.