What product provides straightest look?

Hi, I use a flattening iron to straighten my hair most mornings, and I was wondering what product would be ideal (give the straightest look and hold it for the longest time) for me to put in my hair before I iron.  I have heard wax is good; but will ANY product automatically protect me from heat damage, or will they only do this if it specifically says that on the label?

www.pureology.com, superstraight shampoo, conditioner and serum.

jean32 wrote: Silicones end in the word cone.Silicones protect hair from heat by sealing and smoothing hair's cuticles.Overuse of silicones can cause buildup[residue],silicones can't be washed out with just water.Wax also causes buildup[residue].

And what was the question?

Aquage Beyond Shine. Products with a lot of cones are good heat protectants.