Compact tester for quick checking of water content in brake fluids - results in seconds via LED indicator. Five-level LED scale shows water content from 0%, <1%, 2%, 3% to over 4% - clear warning levels for timely replacement. Compatible with DOT 3, DOT 4 and DOT 5.1 (not suitable for silicone based DOT 5 liquids). Easy to use with just one push of a button - immerse probes, read LED, done. With practical retaining clip for the workshop, vehicle or on the go - ideal for professionals and DIY enthusiasts.