Owners unsure of the condition of their bike’s brake fluid now have a tool to help them determine if they need to flush out their brake system in this Brake Fluid Tester from BikeMaster. Brake fluid is hygroscopic — water absorbing — making it prone to moisture contamination, which can ruin a brake system. Three LEDs built into the tester indicate moisture levels by displaying a red, orange or green light so you can determine whether your fluid needs to be changed. $35.95.