Thule Aion Sling Bag Review

The Thule Aion Sling Bag is a modern-day crossover between a sling and waist pack with added compatibility to Thule’s Aion Backpack line, where it is usable as a dedicated hip belt on their backpacks. It boasts a tube-like shape that can be easily compressed to a low profile or expanded to fit your needs, offering a convenient two-liter capacity.

This sling’s adaptability is what sets it apart from others. Depending on your needs, a simple length adjustment is all it takes to switch between the two carry modes. However, this does seem to limit the overall maximum length it is capable of, especially in crossbody mode. Additionally, the well-thought-out internal organization ensures that everything stays in place and is easily accessible, whether commuting to work or exploring a new destination.

External Components

The Thule Aion Sling Bag’s exterior shell, inner lining, and mesh are all made from 100% recycled polyester. The exterior also has a durable waxed coating on the canvas fabric, designed to develop its unique character as it ages, similar to how leather wallets mature. While this aging process may not appeal to all, it certainly adds a unique and personal touch. In addition to the waxed canvas, there is a non-toxic, water-resistant coating free from harmful PFCs, often used to make products resistant to water, oil, grease, stains, and heat. This sling, as well as all of Thule’s Aion line, are bluesign® certified, a guarantee of protection to workers, consumers, and the environment.

This sling’s main compartment uses dual zippers with a protective AquaGuard® coating for extra resistance to the weather. As for grab handles, a single strip of thin nylon webbing on the top of the bag serves as both a grab handle and a potential attachment point. Aside from that, there are no other lash or attachment points. Thule utilizes minimal branding with just a tiny Hypalon tag with its logo on the front.

The Thule Aion Sling Bag can be used as a crossbody sling or waist pack. As a sling, it tends to sit higher than others we’ve tested, both in the front and the back, which can be an issue depending on an individual’s anatomy and comfort preference. In our experience, this was not a huge issue, but it did require a slight adjustment period, especially when wearing it in the front. Switching from sling bag to waist pack mode is quite simple: all you have to do is adjust it to your waist preference, and that’s it. It can even transition from one to the other while wearing it. However, this simplicity somewhat limits the overall length of the sling. Despite being adjustable on both sides, even at its fullest length, the sling still sits higher than most in our experience.

The strap is quite wide, which may only provide the most comfortable experience for some users. While we found the wide design of the strap to be more cumbersome, others may appreciate the additional weight distribution. The sling features a unique metal closure that does not fall off or slip at all. However, attaching and detaching the closure requires precision, potentially leading to unnecessary fiddling to connect or disconnect it. The back panel provides a fantastic amount of cushion and mesh, providing additional comfort and ventilation, which we definitely appreciate.

Fit Notes

This sling comes in three colorways: Dark Slate, Nutria (a tan or brown-like color), and Black. The interior lining remains the same light blue across all three variations. These muted color options help the bag blend in and not draw too much attention, making it a reasonably minimalistic choice. It is suitable for a wide range of use cases and settings, including city excursions, office environments, or vacations abroad. We appreciate this design as the shape can expand and contract as required, enabling it to sit flush against the body without sticking out too much. However, due to the strap length limitations, those who prefer a looser, lower-hanging sling might not be huge fans of this design, as it sits pretty high up.

Inside The Sling

The Thule Aion Sling Bag features a zippered hidden rear pocket, perfect for securely and discreetly storing essentials like passports, cash, or a wallet. The pocket blends in seamlessly and stays out of sight unless you’re specifically looking for it. It takes up just about the entire back panel, making it quite spacious. Since this pocket is located in the rear and sits up against the body, it is ideal for flatter objects. However, the back panel provides decent padding and cushioning, so placing bulkier or oddly shaped items in this pocket should be fine.

The main compartment of the sling bag has a tube-like shape that can quickly expand to accommodate a variety of items or collapse for a more sleek or minimal fit. This feature is convenient as it does not require additional configuration or setup; it simply expands as needed. This works nicely as a standard storage area for items like a phone, a compact camera, or small headphones. While sunglasses could technically fit in this section, due to the lack of protective padding, we do not recommend that.

There is a key leash with a basic clip in the main compartment. The leash is nylon without any stretch and has a plastic clip to keep keys organized and easily accessible. During our testing, we did find that getting keys on and off can be a bit challenging with one hand, so we recommend using two hands when possible. Depending on how far you need to reach, you can also use the keys while still attached. However, taller individuals may need to bend down or sorority squat in order to get the keys closer, and your mileage may vary.

Against the back wall is a zippered pocket that offers a good amount of storage and the added security of a zipper for smaller items you wouldn’t want loose in the main compartment. The pocket’s mesh material allows the contents to be visible while secured. We find this works well for smaller items like chapstick, change, USB drives, etc.

In front of that zippered pocket, this sling offers a unique approach to additional organization by using a snap button to convert one large slip pocket into two smaller ones. This slip pocket’s padding provides extra protection for stored items. The concept seems pretty helpful in theory but could be more beneficial in practice. It works reasonably well for larger items, but due to the separation being only towards the top of the slip pocket, smaller items tend to slip underneath into the other pocket, making the feature ultimately useless, if not a nuisance. For example, keys attached to the key leash placed in the nearest slip pocket tend to slip under the snap and end up on the other side. Then, we have to slide them back under the snap to get them out.

During testing, we put a wallet in the rear pocket. In the main compartment, we attach keys to the clip and store them in one of the slip pockets, and we use the other slip pocket to store AirPods. We put items like gum and lip balm in the zippered compartment. Although a small bottle of hand sanitizer can fit in this compartment, it begins to get a bit tight. We usually reserved the rest of the main compartment for a phone (in our case, an iPhone 15 Pro Max) or a small compact camera (Ricoh GR 3) with still some space to spare.

The Thule Aion Sling Bag is a versatile, adaptable, and compact sling that can double as a waist pack. Its unique design and recycled materials make it fantastic for daily use and travel. Its ability to transform from a sling to a waist pack makes it ideal for various scenarios, and the thoughtful internal organization ensures that items are secure and easily accessible. The recycled materials and non-toxic, water-resistant coating show Thule’s commitment to sustainability. However, the strap length may limit its appeal for those who prefer a looser or lower-hanging sling. Overall, it is an excellent choice for those in need of a compact, adaptable bag that doesn’t compromise on quality or sustainability.