Engineered to exceed the expectations of the professional electrician the Sperry instruments DM6400 8 function/28 range digital multimeter offers a durable and ergonomic impact resistant design manufactured to the latest industry standards. This unit features a data-hold switch to maintain the reading on the 3.5 in. liquid crystal display and a low battery indicator to ensure you won't get incorrect readings due to low batteries. This unit uses one standard 9 volt battery and includes an auto off function designed to save battery life. Data hold feature captures reading on the display and holds thru multiple tests. Housing is impact resistant and features comfortable and protective rubber boot.