Nicely dressed (up), 6 letters
Flip back and forth, as an on-off switch, 6 letters
On-off switch, e.g., 6 letters
Two-position switch, 6 letters
Any instruction that works first one way and then the other, 6 letters
A hinged switch that can assume either of two positions, 6 letters
It turns something on the first time it is used and then turns it off the next time, 6 letters