The Synapse 25 is a carefully calculated, supremely organized backpack, designed for day hiking, everyday carry, and ultralight travel. Its graceful, curvilinear exterior may on first blush look like something akin to sculpture, but in truth it is simply the judicious realization of ultimate utility. No mesh pockets clutter the exterior of this bag, nor extraneous straps festoon it; in it, you'll be able to carry more than you would imagine, and no one will be the wiser.

The Synapse 25 is designed to fit people from approximately 5'6" to 6'6" / 1.68 to 1.98 m; it is the new big brother to the original Synapse 19 (for those under 5'6" / 1.68 m or who want a smaller bag — check it out). With 30% more volume, we hope to satisfy those who love their smaller Synapse but who need to schlep more stuff or are on the tall or big end of the spectrum.

It features our beloved Edgeless Straps; conformity is overrated — except, perhaps, when it comes to shoulder straps. The edgelessness of this new strap allows it to more softly conform to your shoulder — we (and most people who have worn these straps) find that this increases comfort. Yet the straps aren’t too soft: the 1/2” thick EVAZOTE® OEKO-TEX® certified foam means the strap is robust enough to carry a heavy load.

The front of the Synapse 25 is divided into five zippered pockets, all of which zip shut with #8 YKK Aquaguard® water-repellent zippers:

Though you'd never guess by looking at it, the top center front pocket is deep enough for a 1-liter water bottle or 1-liter hydration bladder (a 2-liter hydration bladder will also fit as long as it's not overfilled). Everyone who has carried a water bottle in a backpack knows how important it is to pack the water bottle wisely so it a) doesn't dig into your back and b) doesn't throw off the weight of the pack. With the water bottle kept in dead center of the Synapse 25, you won't have to worry about either. Removing the water bottle from the Synapse 25 (and replacing it) is a breeze. Note that the water bottle pocket doesn't needlessly continue to the bottom of the bag; that'd be wasted space, plus you'd have to reach farther in to pull your water bottle out. Instead, we took that volume and allocated it to the bottom pocket (where it can serve good instead of evil — see below). Also worth noting: the water bottle pocket has one O-ring. (Yes, we do listen: we're adding O-rings. Just because you asked.)

Below the opening for the bottle pocket is another small zippered pocket, also with one O-ring: it's just deep enough for keys, a wallet, glove liners, or a small camera.

The side pockets are generously sized for sunglasses (in a case or alone), a first aid kit, or even a light Windbreaker-type jacket or down vest compressed in a stuff sack (like our Travel Stuff Sack). The right side pocket has a small organizational pocket; the left pocket has one pen/pencil slot and two wider slots for multitools/knives or just more pens. Both side zippered pockets feature one O-ring — one comes with an 8" / 200 mm Key Strap.

The bottom front pocket of the Synapse 25 is a great spot for extra clothing or snacks and will easily accommodate a thin wool/fleece sweater, light down jacket and/or Windbreaker-type jacket. If you care to add organization, it's more than big enough for a 3D Organizer Cube (Mesh, Halcyon, Parapack, or Clear) or Side Effect; three O-rings are inside this pocket. (Packing advice: tether one of the above-mentioned organizational cubes or Organizer Pouches to the O-rings via a Key Strap.) And because we care about your safety, we've added a 1.5" / 38 mm webbing loop on the exterior bottom of this pocket that's ready to accept the Guardian Light — highly recommended if you ride a bicycle or walk in the dark.

The Synapse 25 has one main, back compartment for large, flat items like notebooks or laptops — it closes with a #10 YKK Aquaguard® water-repellent zipper. It has two O-rings for you to attach Organizer Pouches or Key Straps or tether other items.

Also inside the main compartment are four unobtrusive webbing loops (also known as rail loops), two fore and two aft, to which you can secure the optional Cache (available in sizes specifically for every Apple laptop and iPad; PC users, click here to take a look at our Laptop Fit Guide). When you add the Cache, the Synapse 25 becomes a "checkpoint-friendly" laptop backpack. Here's how it works: on the back (or bottom, depending how you look at it) of the Cache are two parallel "rails" of 1" wide lightweight nylon webbing which extend from the top to the bottom. Included (and already attached for your convenience) with the Cache are two Gatekeeper Rail Clips: unclip the side that isn't clipped to the Cache, slip it through the webbing loops in the Synapse 25 main compartment, and flip it shut. Slip the Cache inside the Synapse 25, and pull it back out: you'll see that the Gatekeeper Rail Clips ride the rails of the Cache, allowing you to remove your laptop or tablet from the Synapse 25 entirely while it is still encased in the protective Cache. Doing this at the airport security checkpoint means the X-ray machines (and TSA personnel) will have a clear, unobstructed view of your device — allowing you to keep your device in the Cache and the whole affair securely held together as one unit. (We think that's much better than having to remove your device and dump it in one of those buckets.) Many of us will appreciate this functionality on a daily basis as well: the rail system can be a convenient and quick way to remove one's laptop or tablet from the bag. And remember, there are four loops of webbing in the top of the main compartment of the Synapse 25: one pair is on the back side, and one pair is on the front side. That means you can choose to have your laptop or tablet against your back or against the front of the bag, whichever seems most comfortable or most convenient. Using all four loops, you could even carry two devices in the Synapse 25. Note that the "checkpoint-friendly" functionality will only work for one of two devices — you'll need to remove the second device at the airport security checkpoint.

In addition to the Cache, the rails loops can also tether the optional Synapse 25 Internal Frame—you can even secure the frame and a Cache to the same set of rail loops. A clever “T” bar holds the loops in place relative to the frame, allowing the lower edge of the internal frame to float freely; in all of our testing, we’ve found this isn’t much of an issue as the bag’s contents tend to keep this lower extreme in place. The frame is constructed of die-cut .060” thick High Density Polyethylene (HDPE), with a nylon webbing sleeve sewn down the center that encases a removable 1” /25mm wide 6061 aluminum stay. We’ve bent the stay to a generic spinal curve but we recommend you re-bend and/or adjust the curvature to best fit your own back (video instruction here). Some folks swear by internal frames and others find them superfluous. For more on internal frames—how they differ from "frame sheets" and the pros and cons of using one—see our Guide To Backpack Frames.

Also inside the main compartment is an elastic-topped, open-top pocket. Generously sized to fit a few books, an extra pair of shoes, or a Tri-Star Medium Packing Cube (for an extra set of clothes — perfect if you're using the Synapse as your personal carry-on item). The open-top pocket will also fit some sizes of Cache, including the 11" Air, iPad, and iPad mini sizes. (If you plan to carry a water bottle in the water bottle pocket and also an iPad or other device in the open-top main compartment pocket, make sure the device is protected with a Cache or a similar protective sleeve: the water bottle pocket is directly in front of the open-top pocket and your device is best protected from your hard water bottle.)

The remainder of the main compartment opens wide — ready to accept whatever larger items you're packing.

For the interior lining of the Synapse 25 we chose 200d Halcyon/nylon because it's ultra-lightweight and ultratough. We've used this fabric for several years now with virtually no complaints or failures; it's been abrasion tested by both our fabric suppliers and our in-house lab. Conclusion? 200d Halcyon/nylon is perhaps a bit of overkill for a lining fabric, and you expect nothing less from us.

The back panel of the Synapse 25 is padded with 1/4", high quality, closed-cell foam with an exterior of Spacer mesh and 210 denier nylon. This combination of mesh and smooth nylon is designed to provide maximum breathability (we even tested it: see here) while still being gentle on your clothing.

The Synapse 25 features adjustable and removable sternum and waist straps with leave-no-trace hardware: if you don't like or don't use your waist or sternum strap, remove them and leave (almost) nothing behind (a design inspired by nature). At the top of the back of the pack, you'll find a webbing loop: use it to hoist the Synapse 25 up and onto your back or to hang it on a coat hook.

Enough said. Now get one and get out of here.