Ultimate Direction started the concept of hydration packs when they created the first waist pack for carrying bottles. A few years later they made the first pack/strap to carry a water bottle in your hand, and have made many other innovations that define what a hydration pack is today.
They continue to be one of the market leaders, with their popularized "vest" concept for carrying water. They also introduced the first women's-specific line of hydration packs, now known as the Jenny Collection that are designed by women for women.
Your favorite body bottle, now with insulation to keep your hot liquids hot, and your cold liquids cold - over twice as long as a regular Body Bottle II 500.