Just a little anecdote 
My dad tried to replace a blown fuse in a Duewi Z-wave dimmer. He proceeded to take the old one out first, in order to see what kind of fuse he had to get as a replacement. To get to the fuse, you have to pull a small plastic tray from the front of the unit behind the faceplate (a nice feature in itself; I have had dimmers that had to be removed from the patress box completely to replace the fuse). To his surprise, the tray held the blown fuse… along with a spare one! Quite a nice touch, I think