Video Overview

Pack Hacker just dropped something we’ve been waiting on for a while — their first-ever product collaboration, built alongside longtime favorite Aer. After 17 months of testing, prototyping, and refining every last detail, the result is the Ultra Sling: a 2-liter everyday carry sling designed to go anywhere and hold up to anything. Big thanks to the Pack Hacker team for pulling back the curtain on the whole design process and delivering something that genuinely pushes what a daily sling can be.

Gear List

• Pack Hacker x Aer Ultra Sling — Purchase on Amazon
• Aer Day Sling 3 — Purchase on Amazon
• MODL Infinity Tool 2.0 — Purchase on Amazon
• YKK Reverse Coil Zipper Pulls — Purchase on Amazon
• Hypalon Webbing & Zipper Pulls — Purchase on Amazon
• Duraflex Swivel Buckle Hardware — Purchase on Amazon
• Compact Travel Umbrella — Purchase on Amazon
• Packable Rain Jacket — Purchase on Amazon
• Aer Cable Kit 2 — Purchase on Amazon

Editor’s Insight

The Pack Hacker x Aer Ultra Sling is the kind of product you don’t rush — and that patience shows in every detail.

At the center of the design is the Challenge Sailcloth Ultra200X fabric, and it’s a serious upgrade over standard nylon slings. The Pack Hacker team field-tested an earlier iteration in Lisbon and got soaked for a week straight, which led directly to this material choice. Ultra200X is renowned in the sailing world for its combination of light weight, UV resistance, and serious weather protection. Pair that with reverse-coil YKK zippers — which physically block water from seeping through — and you’ve got a sling that can handle daily commutes, transit days, and unexpected downpours without complaint.

At 2 liters, the Ultra Sling isn’t trying to replace your main travel bag. It’s built to be the thing that’s always on you. The rounded-rectangle silhouette came from real iteration: early squared edges looked blocky and a bit utilitarian. The final profile is softer, more refined, and wears well regardless of how you’re dressed. This is the kind of sling that doesn’t look out of place at a coffee meeting or on a hiking trail.

The shoulder strap is where the Pack Hacker and Aer teams clearly put the most back-and-forth. Earlier versions had the strap sewn directly into the bag — a design that causes the classic sling problem where the strap bunches and buckles awkwardly at the attachment point. The solution was a Duraflex swivel buckle, which lets the strap pivot naturally with your body, whether you wear it tight across your chest or loose over one shoulder. It’s one of those changes that sounds subtle until you actually wear it for a few hours.

Then there are the lash straps. Tucked flush against the base of the bag, they’re invisible until you need them. Pack Hacker’s suggested use — attaching a MODL Infinity Tool 2.0 on each side to hold an umbrella — is practical and clever. It keeps your bag size-appropriate while adding utility that’s hard to get from a standard sling. The additional loops at the strap anchor points give you even more options for hanging gear or accessories on longer carry days.

The branding is restrained throughout: debossed logos, Hypalon tabs on the straps, and small accent color on the zipper pull tips. It reads as considered rather than corporate. This isn’t a billboard for either brand — it’s just a well-made bag that happens to be a milestone product.

After ten years and 70 tested Aer products, Pack Hacker earned the right to call this one theirs, too. The Ultra Sling is what happens when a review team with strong opinions about gear finally gets to build exactly what they’ve always wanted in a daily carry sling.

Closing Remarks

The Pack Hacker x Aer Ultra Sling is a rare thing in the gear world: a collaboration that actually delivers on the hype. Every material choice, hardware decision, and design iteration has a reason behind it, and it shows in the final product. If you’re in the market for a premium everyday sling that’s built for real use — not just good looks — this one is worth tracking down. Big thanks to Pack Hacker for bringing us along on the full design journey. Check out their channel for in-depth gear reviews, and use the links above to explore the gear that caught your eye.