Description:1.Size: Approx. 15cm/5.9"2.Power Supply: 1 x 1.5V "AAA" Battery (Battery not Included)3.Principle: according to conductivity changes to determine moisture change in brake fluid， with five different color LED indicatorIndicator Description:5 LEDs indicating the water % in the brake fluid:1.0% light indicates that the battery is OK， no replacement2.1% light indicates that moisture content of brake oil less than 1% ， brake fluid has a good performance， and ease of use.3.2% light indicates that moisture content of brake oil less than 2%， brake fluid can be continued to use4.3% light indicates that moisture content of brake oil less than 3% ， proposed to replace brake fluid.5.4% light indicates that moisture content of brake oil less than 4%， brake fluid should be replaced immediately.Note: Due to the difference between different monitors， the picture may not reflect the actual color of the item. Thanks for your understanding.package include1 x Brake Fluid Tester Please Note : This items send out without retail Package