These would be perfect since they are numbered, would you happen to know of a size chart, and at what age do you start using these, I can see the chicks might peck at the colors.? I am trying to keep track of things like which birds have been treated for what and came from where, but when you got 5 or 6 that look the same it's confusing.
Heavy breed roosters, 13
LF roosters, and heavy breed hens 11
LF hens 9
Other then this above, I don't know. I use wire ties until I know they are staying. I have tons of colors. I get them from: http://www.9thtee.com/zipties.htm
What I do is each hatch gets a color. Then if I see a particular bird I like when its young, I will put another color on it to "watch" its progress. You can also make the pullets the right leg, and cockerels the left leg, to see if your guesses are correct when they are older. It very helpful, you just got to remember to track your color system!!!