The "proper" tool would be a spanner wrench that fits into the notches good and snug...
I have no such spanner wrench....
So,...in true "get 'er done with what'cha got" fashion,... I use a small pair of channel lock pliers...
I have also used a small pair of needle nose pliers......
With needle nose pliers, you'll wanna slips the tips into the notches...
I've been on the hunt for some brass M10 x 1.5 hex nuts, that are small enough to use here. No luck, so far.....
It's not that difficult, either way.
