GOSSAMER GEAR G4-20 Ultralight 42 Backpack - is 42 litre fully frameless backpack with design based on one of Gossamer Gear old design G4 which was one of the original ultralight backpack. It uses updated materials and technology.
Gossamer puts a weight limit on the pack of 14 kg (30 pounds), we recommend using this pack at around the 9-11 kg (20 to 25 pounds) to be comfortable out on the trail.

The closure system is roll-top closure, you can buckle it on top like a dry bag or on the sides and secure with loop over strap on the top and you can attach stuff to it like a wet jacket.
On side of the backpack you've got completely removable compression cordage to help compress the load and secure stuff on the outside or you can easily remove it. 

Front zippered pocket which is not huge, but you can fit some small essentials in, you could put car keys, snacks, gloves in and anything that you want quick and easy access  - it is a nice little feature it is pretty convenient.

Stretchy mesh front pocket you can fit a bunch of stuff in, it's really breathable if you want to dry out a wet gear and continue the drying process while you hike.

Hip belt on G4-20 is not removable and has 2 zippered pocket to keep small items like cell phone, snack bar, or compass close at hand.

Asymmetrical side pockets where one is in regular height and second one of the pocket is quite a bit taller and it's actually designed to store for example a shelter or any taller items that you might want to put in there whether that be poles for your tent or anything like that.

There is no internal frame like most of GG other packs instead they rely on really thick piece of foam back pad with a new design as the only form of support for the pack. It's very comfortable when you're wearing the pack and it does add a good level of rigidity to the backpack. It can be used as a sit pad as well. However it is a frameless pack but it still has a fully supportive hip belt so it is a really nice compromise.

This pack is going to be absolutely fine for the majority of your fast and light trips with dialed-in ultralight gear. This pack will be great also for PCT or AT, it will carry food for 3-4 days very comfortably with a standard kind of ultralight backpacking setup.

MATERIAL: 70D & 100D Robic Nylon, DWR coating

WEIGHT (medium)

Pack: 613 g / 21.6 oz

Molded G Sit Pad: 89 g / 3.1 oz

Total:  702 g / 24.7 oz

CAPACITY (MEDIUM)

Total: 42 L

Main Pack Body to Bottom of Extension Collar: 30 L

Mesh and Side Pockets: 12 L

MAX CARRY CAPACITY:  14kg / 30 lbs

FOR COMFORT: 11kg / 25 lbs

CHARACTERISTIC

• Extendable roll-top with dual closure options.
• Removable molded cushy sitpad.
• Fixed hip belt with two zippered hip belt pockets.
• 1.5" hip belt webbing for max comfort.