Gridfinity battery holder, can hold AA, AAA, CR2032 and 9V. 2by3 gridfinity bin and 2by1 gridfinity bin (2by1 doesn't have CR2032). Normal size has 12 AAs, 14 AAAs, 4 9Vs and 7 CR2032s. Extra AAAs has 12 AAs, 24 AAAs, 2 9Vs and 7 CR2032s. Small version (2 by1) has 3 AAs, 8 AAAs and 2 9Vs.