For use with Alice 1, 2 and 3. This is a 3.6v lithium METAL battery. This is NOT the correct lithium battery for use on Alice 4.0. Although the Alice 1, 2 and 3 use only one battery, we ship two as lithium batteries have a “sleep” issue and do not always wake up, so we send two to be sure that one will wake up. (If the first one works fine, keep the other on hand as a spare.)