Max Alkaline D Batteries provide a long-lasting power source for such common workplace devices as calculators, pencil sharpeners, cameras, flashlights and portable tape recorders. They also hold their power for up to 10 years while in storage so you have power when you need it most. Batteries are date-coded and 100 percent mercury-free.Max Alkaline D Batteries provide a long-lasting power source for such common workplace devices as calculators, pencil sharpeners, cameras, flashlights and portable tape recorders. They also hold their power for up to 10 years while in storage so you have power when you need it most. Batteries are date-coded and 100 percent mercury-free.