it's silicone free, and specifically designed to leave no "build up"
Not sure about the other ingredients though, the list is:
Aqua, Sodium Laureth Sulfate, Sodium Lauryl Sulfate, Cocamidopropyl Betaine, Sodium Citrate, Parfum, Sodium Xylenesulfonate, Sodium Chloride, Citric Acid, Sodium Benzoate, Tetrasodium EDTA, Propylene Glycol, Hexyl Cinnamal, Hydroxypropyl Methylcellulose, Linalool, Benzyl Salicylate, Limonene, Magnesium Nitrate, Aloe Barbadensis Leaf Juice, Anigozanthos Flavidus Extract, Phenoxyethanol, Ethylparaben, Methylchloroisothiazolinone, CI 19140, Methylparaben, Magnesium Chloride, Butylparaben, Methylisothiazolinone, CI 17200, Propylparaben, Ascorbic Acid, Sodium Sulfite, Potassium Sorbate.
I don't really know what these ingredients are! But I know silicone is usually on the label as "dimethicone" or "cyclomethicone" and can't see those on the list.
REN is very good for products without any "nasties" and their shampoo is silicone free and very pure, no SLS either, but a bit more pricey!