Alkaline batteries give at least 2.5 X longer life than cheaper Carbon Zinc (so called Heavy Duty) batteries. Volkano batteries are environmentally friendly with 0% Mercury. Volkano batteries have a guaranteed 5 year shelf life. Volkano batteries have been tested to have less than a 0.00002% failure or leakage rate. Tamper proof packaging reduces in-store shrinkage Features Model VK-8101-BL