This N Size Clock Battery is sometimes hard to find. These N Batteries are a Quartz Accessory that we carry for some of the quartz inserts. Almost like a camera battery, this size is shorter than the AAA but about the same thickness as the AA. Often times people will purchase ones that are similar, however they quickly realize it is a slightly different size. By purchasing this you will save a lot of time and aggravation running to the store trying to get the correct fit.