I mark all Self-centring chucks with centre punch marks on their outer face, corresponding to the jaw number.
This new 4 jaw S.C. chuck got marked before its first use.
I'll never have to try and find the numbers marked inside the grooves. Jaw changing will always be a lot quicker.
You can just see centre punch marks for jaws 1, 4 and 3 on the face of this new chuck.