Originally Posted by ColonelSanders

With my Mirrycle Mirror, it has an expander that braces itself against the inside of your flat handlebar and you need an allen key to expand it out and to take it off the bike.

It is not an item I ever remove from my bike when I lock it up(unlike my lights), and I am not worried about anyone stealing it.

https://www.mirrycle.com/mirrycle_mirrors.php