The difference between the Selector and Router is that when you change the Selector to a new position, it sends whatever value was last received there (even if it's not currently being received) - while changing the position on the Router only "opens that pathway" to allow something new to pass though (nothing is sent until new values arrive at that input).
Selector module can be used to scale values from 0..1 range to any other range, defined by two input values, e.g. -10..40. See thread on User Forum
