GE Power 1200mAh 40c (Zius BK2S)

This GE Power 1200mAh 40C battery is sized and ordered specifically to fit the Zius BK2S blaster's battery compartment, which is the part that usually trips people up when shopping for a replacement — a battery that's the right voltage but the wrong physical size just won't close the compartment. GE Power spec'd this one to be the maximum possible mAh capacity that still fits inside the BK2S, so you're not leaving runtime on the table by going with a smaller pack that fits with room to spare.

With a 40C discharge rating, it's built to handle a higher current draw without sagging under load, so performance stays consistent even when the blaster is working hard. If your stock or aging battery is underperforming or won't hold a charge, this is a straightforward drop-in replacement sized for exactly this blaster — no cutting foam or forcing the compartment shut.