D batteries are commonly used in portable music systems, large torches and flashlights, for ignition systems for gas heaters, irrigation controllers, and toys. Alkaline batteries have a shelf life of approximately 6 years, while AD batteries are 61 mm long and 34 mm in diameter and weigh 139 grams. They are also available in the HR20 rechargeable model, with the same diameter and thickness; their weight varies depending on the model's capacity. Like the entire range of rechargeable batteries, their voltage is 1.2 volts and their mAh capacity can vary depending on the brand and model.
