The following 6-volt batteries can be used for your Ion or SpaceShot headlamp: Duracell 28L (lithium), Duracell 28A (alkaline), Black Diamond 6-volt replacement (silver oxide), Radio Shack 2cr 1/3 N (lithium), and Kodak K28L (lithium). It's important to note that lithium batteries have a longer shelf life and are less prone to leaking than alkaline batteries, making them a better choice for long-term storage. Always make sure to follow the manufacturer's instructions when replacing the batteries in your headlamp.