Absolutely loved this stuff- I've never been a fan of leave in conditioned because I always felt it weighted down my very fine but thick, straight, uncolored hair. This was absolutely the opposite-- made my hair look better than ever.

All the Kerastase products are amazing. I use the shamppo and leaving in treatment daily. Sample was small as most of the Birchbox Samples have become.

This product does exactly what it says it will do. No gimmicks, no jokes. I have baby fine hair, and at first I was using too much product and it was weighing my hair down, but I just let up on the amount I was using and was amazed how much healthier my hair was! Plus it made my samples last longer :)

I have thin, delicate hair from highlighting and I always use a blowdryer. This protects it without weighing it down!!!

I found out about this stuff when I was living in Spain. I went to the beach EVERY day and my hair was suffering -- and my wedding was approaching fast. My stylist suggested this, actually the whole Resistance treatment line (in the green bottles), and after using the entire system I can actually say my hair was changed for the better. Visible results people. How often can you say that? Pretty much never.
One thing this does in particular is seal the ends when you blow dry. The ends are just calmer, look more polished. It is a gel and it is completely non-greasy, smells great, a little goes a long way.
I think this product works like a champ alone, but along with the other products on this line (not sure if they're available on Birchbox, I'll have to look), it's just fantastic!

This heat protectant is great. Great for dry hair, or chemically treated hair. I get Keratin treatments, and I think it went hand in hand with protecting my hair from heat. Smells great, also.

I have thick, curly hair that is colored. After using this product, my hair was smooth, shiny, and smelled fabulous. I tend to heat style my hair; blow drying & large barrel curling iron. I whole-heartily recommend this product.

This product is the right amount of moisture for your hair without causing it to be oily. It has a nice light scent and after using it, your hair looks healthy (even the ends!)

I mean, why use this stuff that's full of chemicals when you can buy some coconut oil from the grocery store and get the same results? It works, but I feel like you're paying for the prestige of the name, not any special final outcome.

I enjoy the Kerastase brand products. I already owned this before receiving it in my box. It was nice to get a travel size packet for my next trip.