I use colored zip toes, the 7" as opposed to the 4" though both can work. Just clip the excess length off whichever kind you use. I used to use the hard plastic rings but did not like those very much. With anything around the leg you have to monitor it so it doesn't get too tight. Those hard plastic ones were hard on my arthritic fingers to get off, even harder than putting them on. And one size doesn't fit all, You have to have the right size or you can get SueT"s problem, they can come off. When I got my rings I got packets by color and by size so I needed many packets. With the zip ties you tighten them up to fit. Simpler.
I'll say this again. No matter what you use you need to monitor the to make sure they don't get too tight. That's zip ties or hard plastic rings. I use wire cutters to cut the zip ties off when they start to get tight and need to be replaced.
You'll need to come up with your own color code system. I used the color on the left leg to tell me what year they hatched. Then I'd use the color or color combination on the right leg to identify which specific chicken it was. Of course, if some are black and others are red you can use the same color combinations on them. For example a red chicken with a green zip tie on its left leg to signify 2018 an a yellow and a red band on its right leg was a different chicken that a red one with a yellow tie on the left leg for 2019 and a yellow and a red on the right leg.
Just keep notes, it's not that complicated.
I'll say this again. No matter what you use you need to monitor the to make sure they don't get too tight. That's zip ties or hard plastic rings. I use wire cutters to cut the zip ties off when they start to get tight and need to be replaced.
You'll need to come up with your own color code system. I used the color on the left leg to tell me what year they hatched. Then I'd use the color or color combination on the right leg to identify which specific chicken it was. Of course, if some are black and others are red you can use the same color combinations on them. For example a red chicken with a green zip tie on its left leg to signify 2018 an a yellow and a red band on its right leg was a different chicken that a red one with a yellow tie on the left leg for 2019 and a yellow and a red on the right leg.
Just keep notes, it's not that complicated.