Redken Smooth Down Heat Glide 5 oz Smooth Down Heat Glide Protective smoother is a leave-in serum that provides heat-safe control to tame frizz on even the most unruly hair. Gives an ultra-smooth, glossy finish. Can be used with or without heat. Heat protective serum smooths and tames frizz on even the most rebellious hair. Leaves hair smooth and shiny with a lightweight, frizz-free finish. When used with heat, smoothing and shine are intensified.