To be honest I don’t like using them but I have kept 4 babies 3 from one mother 1 from the other but same fatherI believe you are referring to 'band' size. If your parrot is pick at the plastic band and causing it to degrade a metal band can be used. But, the industry have long ago stopped use metal bands as they can be a source of very serious issue when they become caught. Sadly, the Parrot either breaks the leg or causes trauma to a point that the parrot dies.
If the plastic bands didn't work, neither will the leather, that will be chewed away for sure.To be honest I don’t like using them but I have kept 4 babies 3 from one mother 1 from the other but same father
I Also have 2 other males 9 altogether
So I’m forced to use them for ID to stop inter breeding
I’ve just seen the leather ones so might try them
The last time I looked for the bands they were mainly aluminium
I tried the plastic clip ones but they didn’t last long