Flexii Battery Capacity checker as the name goes helps to check the user how much juice more is left in the battery so that you can replace it with fresh ones. Personally I don’t think I’ll include this in my arsenal but those of you interested, it works with AA-size battery, AAA-size battery, C-size battery, D-size battery, 9V battery, button cell battery, alkaline battery, lithium battery, rechargeable battery.

Available for $15 from Vavolo.