Football Officials' Whistles

[jimpiano]

I noticed during the Super Bowl that Terry McAuley wears his whistle on his hand. In a couple of pictures in the papers today there were shots of McAuley in the middle of scuffling players but the whistle was in his mouth.

I assume this is to prevent injury when using his hands to pull players off each other. Does the Whistle just disengage from the ring around his finger or does he have to remove the entire apparatus(the pictures were hard to tell)??

What are the strengths of using a whistle on your hand? One that comes to mind for me is with a whistle on your hand you would not be blowing it until you were sure the play was over. (Obviously I am not a football official)

Just wondering and have been for a long time since I have seen both types of whistles used by officials at each position.

Thanks in advance.