Sturdy 4 AA battery holder for your Arduino project! Provides 6V output when used Alkaline batteries, approx 4.8V when used with rechargeable AA. These AA battery holders feature a 2.1mm x 5.5mm power plug on a 4 inch cable. The case is made from ABS plastic with nickel plated springs to hold your AA batteries in place. Each battery holder measures 3.6" x 2.3" x 0.59"( 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