Although a deters the number of keys first, this switch has a surprisingly easy to use and the one-sided guide explains just about everything you need to know. So I imagine a timer! Another point that the built-in battery saves the settings. And since the only shortcoming is equal to the game: the battery can not be replaced. Something like you declare as "normal product cycle" - but could also make it more customer-friendly with very little extra effort. Let's see how long the battery is serving.
