Multi Purpose Use - can be used to test different type of household batteries like AA, AAA, C, D, 1.5V,9V and button type Require on Battery - activated by the battery being checked, no battery needed for operation Simple but Effective - compact size and lightweight, portable effective battery tester, a must buy for anyone who uses regular or rechargeable batteries on a regular basis Easy to Use - identify battery status simply by the analog display needle, "good" (green), "low" (yellow), and "replace/recharge" (red)