• Comparative electrolytic type tester.• Checks moisture content of fluid by resistance to electric current.• Easily calibrated using new brake fluid.• Audible test cycle with three LED read-out.• Just insert probe and press-button for immediate result.• Works on DOT 3, 4 and 5.1 specification fluids.• Powered by a 9V battery (not included).Comparative electrolytic type tester. Checks moisture content of fluid by resistance to electric current. Easily calibrated using new brake fluid. Audible test cycle with three LED read-out. Just insert probe and press button for immediate result. Works on DOT 3, 4 and 5.1 specification fluids. Powered by a 9V battery (not included).• Comparative electrolytic type tester. • Checks moisture content of fluid by resistance to electric current. • Easily calibrated using new brake fluid. • Audible test cycle with three LED read-out. • Just insert probe and press-button for immediate result. • Works on DOT 3, 4 and 5.1 specification fluids. • Powered by a