Instead of buying several trail packs in quick succession after realizing yours are always too big, too small, or without a feature you didn't realize you needed, you could invest in a pack like Shimano's Unzen 4 Enduro Hydration Pack with Reservoir. With a Hydrapak hydration system and the ability to hold and organize everything you'll need on a ride, the Unzen offers a versatile size that won't weigh you down on short days, but will still hold everything you need on longer adventures. The bag's tool organizer pocket, fleece-lined pouch that protects the surfaces of electronics and sunglasses, and space to store lightweight body armor or a jacket on its exterior help it get the job done whether you're pedaling along your local singletrack or traveling further afield. It's also dotted with an array of other more general-use pockets as well as an outer helmet holder to make packing up for a drive to the trailhead easier. A removable waist belt helps keep the ache out of your shoulders on longer days, even when the pack is laden with supplies. While your stuff stays organized, you'll stay cool and dry with the bag's breathable straps and back panel, designed to keep you comfortable during hot days and exposed rides.