There you go - RS import from Japan - metric fittngs only, they abhor feet and inches.
A 9 or 10mm drill is wee bit big for a pin chuck. So I take the chuck off the power drill too. Or use one of those old cranked brace and bit tools.
The push fit knobs lack the grub screw for fitting to unsplined plain shafts, yes you can drill them out but imo nicer to buy new ones that fit proper like.
There's two kinds of people, those that hear the music and those that don't.