Available in four strengths: 2x for sensitive skin, 3x for normal skin, 5x for tolerant skin, 10x for advanced treatment. Topix Replenix All-Trans Retinol Smoothing Serum 5x is a lightweight, antioxidant-rich serum designed to smooth and firm up your skin. Its special ingredients boost radiance and neutralize free radicals. Sagging skin is lifted, hyperpigmentation is diminished, the signs of aging are minimized and firmness and elasticity are increased. Rough dry areas become softer and smoother with their luminosity restored. This product is appropriate for acclimated skin types.