I started using the ABA leg bands last year. You have to order your bands early, they will run out of one size. That happened to me, had to order the next size larger.
I already have my bands for this year, I ordered early. You have to keep trying each week as the birds grow to get the bands to stay on. Now that I am using them, I can't see myself not using them. Those metal bands are just to clumsy and hard to read if they get bent a little bit.
Last year bands were bright yellow, this years bands are blue.
Also any bantam bird with the right size ABA band on, and that bird wins at an ABA, show gets a prize from the ABA.
The ABA seems to award those prizes with or without the band if you are a member. I am an ABA/APA judge and I have never been instructed to make any notes about a bird with an ABA seamless band. There is no special place on the ABA report form to note that....but I vaguely remember hearing that before.
I just checked the ABA judging instructions and don't see a note about seamless bands.
Walt