The Thermasilk leave-in conditioner is the only product that has ever done a good job of protecting my hair from heat styling damage. Biosilk doesn't even come close. I went through hell to get my last bottle of Thermasilk on the airplane with me when I flew back to San Diego from the Bay Area. I actually had to go find a box to put it in to check it!! And now it's discontinued. For everyone who loved Thermasilk, there are still a few online shops where you can buy the remaining bottles that are left. Drugstore.com and BeautyBuys.com are a couple of them. Good luck! I'm getting a case of the leave-in conditioning spray.