Does your device work intermittently? This may be due to contact resistance, when nickel flakes off the battery terminal and interrupts the flow of electricity to your device. Panasonic’s original Special Tough Coating is a nickel-iron alloy that reduces contact resistance, optimizing energy flow and keeping your appliances working at their best. Special Tough Coating is a nickel-iron alloy technology that maintains a smooth flow of power from battery to device.