Banded chickens?

[Mary Of Exeter]

I've noticed some pictures of chickens with seamless bands on their legs. A lot of them look like the NPA bands I put on my pigeons, just a larger size. Plastic or metal.
Does anyone do this? It'd probably make breeding records easier if you're going for a certain trait(s). I already knew of the crimp on metal tags.

 

[debilorrah]

I purchased a chicken with a band on her leg, and it turned out she was a show bird. Then she got older and got this really weird toenail growing problem - they never stop!!!! We cut the band off.