Retinol Plus Smoothing Serum 10x is a yellowish silicone-based cream with a leafy tea scent. The serum requires a bit of rubbing in but it quickly absorbs to a velvety matte finish. The formula contains retinol (1%), green tea and caffeine. The retinol in this product visibly smoothes and evens out the complexion while the green tea and caffeine provide the skin with antioxidant protection. This is the most potent retinol formulation in the Topix Replenix line and those not accustomed to high levels of retinol may experience peeling, redness and irritation when using this product. The serum is also available in 3 lesser strengths: 5x for tolerant skin, 3x for normal skin and 2x for sensitive skin.