Great 4 AA battery holder for your Arduino project! These are great for replacements for electronic devices that have a lost or damaged battery holder. Provides 6V output when used Alkaline batteries, 4.8V when used with rechargeable AA. These AA battery holders feature a standard snap connector on one end. The case is made from ABS plastic with nickel plated springs to hold your AA batteries in place. Each battery holder measures 2 3/8" x 1" x 1 1/4"( L * W * H ). AA batteries in these holders will last much longer than a standard 9V battery will when powering up electronic projects. AA batteries not included