Phoenix System's BrakeStrip CU+ID comes as two patented brake fluid tests in one strip. The strips show if the brake fluid should be changed as part of a brake flush service. These strips test for MAP guidelines for copper and DOT brake fluid type. Brake fluid has hygroscopic properties which attracts water vapor from the atmosphere, which gets into the fluid and cause deterioration inside the brake system. This increases levels of copper, which the strip checks for. Increase brake flush sales with confidence.