16mm Solid Carbide Router Bit - wood materials

Hi.

I am a newbie here and hope not to stand on anyone's toes.

So we have only really traded in bits sizes up to 12.7mm shank but a customer asked for 16mm bits which we resourced but there are some questions I'd like to ask you.

Really I have no experience with the bigger size tooling.

Have attached a pic.

1.) What is the purpose of the clip on the end of the shank...?
2.) As I understand the length of the shank into the collet should be about 2 x 16mm;
however the grind of the flute runs out about 24mm from the end of the shank (as shown in pic).
Surely the collet shouldn't slip over the run-out of the flute....??? Should this length not be at least 32mm to 35mm minimum............??

Can anyone help me out with the above...? Would be greatly appreciated.