Reverse Curl Form

Im adding these back in my routine and Ive never been certain about the form. Basically should my wrist be bent up or down at all and should it move?

My guess is no and no but Ive seen it done a million ways and probably tried half of them, not sure except if it felt right that day. I have really only thrown them in here and there, never done them regularly, so looking for advice. Thanks.

Keep your wrists in line with your arm, so don’t purposely angle it down/up. At least this is how I best felt it. Also, try not wrapping your thumbs around (suicide grip). Those kill.