3 In 1 multi function tester. Digital tyre gauge that records the pressure of all 4 tyres for later reference. The tester is supplied with a plug accesory plug that tests battery & alternator condition. The battery voltage tester displays the battery condition in volts. The alternator test will display the condition of the alternator, low, charge & over. This portable device is ideal for all road users as well as caravans & campers running auxiliary batteries.