What do salons used after the conditioner is rinsed to make ethnic hair lay & straighten good when flat ironed?

i jus started at a salon but dont kno what to go buy for that.What do salons used after the conditioner is rinsed to make ethnic hair lay %26amp; straighten good when flat ironed?
Ask around at other ethnic salonsWhat do salons used after the conditioner is rinsed to make ethnic hair lay %26amp; straighten good when flat ironed?
Some use heat protectant, some don't but what i've noticed is the tongs they used it's a different material and they use that thing to heat it up