The most critical factor is the DEET concentration percentage, which typically ranges from 10% to 100%. Higher concentrations do not offer 'stronger' protection but rather longer-lasting protection (e.g., 30% DEET provides roughly 6 hours of protection). You must also verify the delivery mechanism (aerosol spray, pump spray, lotion, or wipes) and ensure the solvent base is compatible with your target market's preferences, such as water-based formulas for reduced skin irritation or alcohol-based for quick drying.