Flat Ironing Natural Roots Aka New Growth

Good day! What temperature setting do you use to flat iron natural hair? Im transitioning and my relaxed hair comes straight with 320 degrees on the flat iron. But the roots get puffy after a few days. I dont care about heat damaging the curl pattern. I just want to keep the roots straight. What are some good products to use?

I’m a fan of the Beautiful Textures Texture Manageability System. It works like a dream to keep my hair straighter for longer. I also like Paul Mitchell Super Skinny serum for a heat protectant. It’s not too heavy and it does the trick.

Thank you