Heat Protecting Serum

heat protecting serum
What heat-protecting serum or spray do you swear by?

I have used a few different ones, and they are all mediocre at best. Which ones do you all use? I have thick, curly, fine hair:)

i have wavy, medium-thick hair, and i swear by guardian angel for each n flatten by spray got 2b. it's pretty much amazing. : D

Flat Ironing natural curly hair straight with a ghd