The front of the Synapse is divided into five zippered pockets all of which zip shut with #8 YKK splash-proof zippers; we chose to add quiet cord pulls to the zippers to prevent the rattling "I'm being followed by a Golden Retriever" sound associated with metal zipper pulls - important to maintain quiet in the woods, mountains, or in your business meeting.

Though you'd never guess by looking at it, the top center front pocket is deep enough for a 1-liter water bottle (SIGG, Nalgene, or any type of 1-liter or smaller water bottle should fit.) Everyone who has carried a water bottle and a backpack knows how important it is to pack the water bottle wisely so that 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, you won't have to worry about either. Removing the water bottle from the Synapse (and placing it back in) is a breeze.

Beneath the opening for the bottle pocket is another small zippered pocket: just deep enough for a small wallet or a Swiss Army knife.

The side pockets are generously sized for sun glasses (in a case or alone), a small first aid kit, or even a light windbreaker or down vest. The right side pocket has a waterproof Ultrsuede-lined inner pocket for iPhone or other cell phone or iPod; the left pocket has three pen/pencil slots. Both side zippered pockets feature one o-ring. One o-ring comes with an 8" Key Strap.

The bottom front pocket of the Synapse is big enough for a 3D Clear Organizer Cube or Side Effect and extra T-shirt or lunch; it has one "o-ring".

The Synapse has one main compartment. Inside the main compartment is an open-top pocket sized to fit a book, a Netbook inside of a Cache sleeve, or a Kindle inside of the Padded Organizer Pouch. If you plan to carry a water bottle in the water bottle pocket and also a Netbook or Kindle in the open-top main compartment pocket, make sure the Netbook is protected with a Cache or the Kindle is protected Padded Organizer Pouch, or similar protective sleeves. The water bottle pocket is directly in front of the open-top pocket. This pocket is also great for packing an extra set of clothes - perfect if you're using the Synapse as your personal carry-on item. The remainder of the main compartment opens wide - ready to accept the larger items that you're packing. The main compartment will even fit smaller 13" laptops such as the 13" Macbook, 13" MacBook Pro, or MacBook Air. Because the Synapse doesn't have built-in padding for these laptops, we recommend protecting them by first putting them inside of our Cache sleeve - and then inside of the Synapse.

The main compartment of the Synapse has two o-rings. If you're new to our bags, you may be wondering - what's all this talk about o-rings? They are just as they sound: small, plastic "o" shaped rings that are sewn inside of the compartments and pockets of our bags. Clip an extra Key Strap to an o-ring to keep track of an extra set of keys or your work or school ID. Clear, Padded, Cork, or Cordura Organizer Pouches can be clipped to o-rings to add further (and color-coded) organization. A Guardian Light can be clipped to an o-ring to serve as an interior bag light. Clip a 3D Clear Organizer Cube via a Key Strap to an o-ring, and you have a TSA 3-1-1 liquids bag on a tether - making sure you won't lose it when going through the airport security line. There are endless uses for o-rings and the accessories that clip to them.

Most color combinations of Synapse are made with an exterior of 1000 denier Cordura and interior of Dyneema/nylon fabric, made especially for us in Japan. The Synapse is also available with a Steel Dyneema/nylon exterior and Solar Dyneema/nylon interior for those who want to travel ultra-light. We choose to line our bags with Dyneema/nylon because it's ultra-lightweight. But we also wanted to make sure it was ultra-tough, so we asked one of the fabric mills we work closely with to perform abrasian tests on it. The results? It's tough stuff - plenty tough to serve as an exterior fabric for most folks (though not quite as abrasion-resistant as Cordura), and more than tough enough to serve as a lining fabric.

The back panel of the Synapse is padded with 1/4", high quality, closed-cell foam with exterior of Dri-Lex Aero-Spacer mesh and 420 denier nylon. This new combination of mesh and 420 denier nylon is designed to provide maximum breathability while still being gentle on most fibers used in clothing. The backpack straps of the Synapse were custom-designed by Tom to fit folks from 5'0" - 6'0". We tested the Synapse backpack straps on a wide range of people - all heights, shapes, and sizes - and we think we've come up with straps that work for just about anyone: no small feat! The Synapse features adjustable and removable sternum and waist straps that leave no trace of hardware behind when removed. At the top of the back of the back, you'll find a webbing grab handle.