Battery Size: 1.5V | 9V Good: 1.5V ~ 1.28V| 9V ~ 7.8V. To test all different kinds of batteries (AA, AAA, C, D, 9V, mini cell). Test multiple sizes of batteries in one unit. (1.5V: AAA, HP16, MN2400, R03, AA, HP7, MN1500, UM3, C, HP11, MN1400, SP11, LR14, UM2, D, HP2, MN1300, SP2, R20, UM1; 9V: PP3, MN1604, 6F22, 006P).