This kit comes with 4 AA batteries and 4 AAA batteries. They are all from the trusted name Duracell and you can keep track of these batteries by using the battery tester included! This battery tester also tests 9V, Button Cell, AAA, AA, C, and D batteries. Tests Button Cell To Aaa, Aa, C, D & 9 Volt Batteries are genuine Duracell - one of the most trusted battery brands!These alkaline batteries are standard sizing for most toys, electronics, tools and more!You can use the tester for most batteries - not just the ones includedUniversal tester measures only 4.25 inches - you can keep it on hand with you anywhere