I've had problems with my tags falling off or getting caught on things (which sends the dog into a panic) so I switched to collars with brass ID plates. Gun Dog Supply puts ID plates on for free. Not the best quality collars or plates, but still not a bad deal! Mine read like this:
ANIMAL NAME - OWNER NAME
[our number]
[second cell number]
IF AUG, [cottage number where we are in August]
Nikon, doing a track wearing his ID collar

My tags had more lines and two sides so had a lot more info, but like I said they don't stay on. I've had people call my cell and tell me that they found my dogs' tags and clipped them to a fence at the park.

http://vankelderdogs.dutchbingo.net
http://www.schhmi.com