Wella Welloxon Perfect 9% 30 Vol Emulsion Developer Activator Oxydant 33.8 Ounce 1000 Milliliters designed to be used with the Koleston Perfect Me+ Permanent Hair Color. Welloxon Developer has been specifically formulated to achieve the most accurate color results. Welloxon Perfect Developer promotes easy and fast mixing and easy rinsing, as well as precise application and foil adhesion. Simple 1:1 mixing ratio and 35 to 45 minutes to process with up to 100% grey/white hair coverage. Simple mixing 1:1 ratio. ATTENTION: These products require professional expertise. Seller is not liable for any adverse outcome resulting from the use of this product.