Not all Hyaluronic Acid serums are built the same — and the difference is molecular weight. The Isntree Ultra Low Molecular Hyaluronic Acid Serum uses 14 distinct types of HA spanning from ultra-low (329 Daltons) to high molecular weight, working at different skin depths to hydrate from the surface down to the deeper dermal layers simultaneously. It's the most comprehensive HA delivery system in a single serum that Sul Skin has come across.

The base is mineral-rich deep sea water from Ulleung Island, off the east coast of Korea — rich in magnesium, calcium, potassium, and other trace minerals that help the skin retain moisture and maintain barrier integrity. The 14 HA forms include the complete spectrum: Hydrolyzed Hyaluronic Acid, Sodium Hyaluronate, Potassium Hyaluronate, Sodium Acetylated Hyaluronate, Hydroxypropyltrimonium Hyaluronate, Sodium Hyaluronate Crosspolymer, Dimethylsilanol Hyaluronate, Hydrolyzed Calcium Hyaluronate, and more — each with a specific role in the hydration cascade.

Glyceryl Glucoside is a skin-activating ingredient that stimulates aquaporin channels — the water transport proteins in skin cells — to draw moisture more deeply and efficiently. Madecassoside (from Centella Asiatica) provides anti-inflammatory support, and Beta-Glucan reinforces and repairs the moisture barrier. Panthenol and Allantoin round out the soothing layer.

The formula is fragrance-free, silicone-free, and vegan. The texture is a clear, water-thin gel that absorbs in under three seconds without any tackiness.

This is the HA serum for people who've tried HA serums and found them underwhelming. Sul Skin recommends it for dehydrated skin of all types — dry, oily, or combination — and particularly for anyone whose skin looks dull and tight despite using moisturiser.