What is a curb chain for?

[xxxkristinaxxx]

Hi, just like to know what a curb chain is for and how should it be fitted?
Thanks x

[Mehitabel]

it's to apply pressure to the curb groove when the rein is pulled, which asks the horse to flex and soften the jaw and bring the nose in. also to limit the amount of poll pressure a bit can give. it should be fitted so that it starts coming into play when the shank is swivelled 45 degrees.

[xxxkristinaxxx]

Thanks x