Best hair smoothing serum/oil/product?

[lilacpaintedview]

Just wondered what yours is? I have fine highlighted hair that can get a bit of frizz!

Tresemme 7 day straight is good. I got it on offer in superdrug.

I like L'oreal Extraordinary Oil. Just as good as the (much more expensive) Kerastase equivalent. They do one for fine hair - I spray on when wet, blow dry, then use a little to tame any frizzy bits.

m.boots.com/h5/cat_hub?path=%2Fen%2FLOreal-Elvive-Extraordinary-Oil-Mist-Fine-100ml_1330305%2F&unCountry=uk