When you need the power, versatility, and ruggedness of our powerhouse waterproof Apex headlamp, but youre looking for a lighter weight option, you need the Apex Pro. The slimmed down Apex Pro was designed with the unique and ever evolving needs of professional runners and extreme adventurers in mind. The Apex Pro is powered by 2 CR123 lithium batteries protected in a highly durable and waterproof housing. Not only lighter in weight, lithium batteries are better suited for cold weather. Built for professionals, perfect for all users.