It is used on the webbing between the toes.The ones they sell are small [I loose them ] and you have to be careful to not just put a hole in the web as it will heal shut.It needs to cut the edge.I find a ear notcher for hogs works better for me.Available at most farm stores.I painted mine orange so I can find them easier.Use then at hatch.At what age do you use a toe punch? I have just gotten into chickens and plan on hatching a lot in the spring. I was wondering about how to use this system. Has anyone made an instruction article on BYC?