Boundary Supply Rennen Sling Review (Updated 2022)

Boundary Supply Rennen Sling Review
(Updated 2023)

In this Boundary Supply Rennen Sling review, you’ll find how durable yet sustainable it is. 

What’s interesting about this crossbody/sling is that it’s made with RE–3™ Cordura® Eco body fabric. Speaking of being eco-friendly, it takes exactly 11 plastic bottles to make its exterior fabric. 

Watch our epic Boundary Supply Rennen Sling review below! 👇

Boundary Supply Rennen Sling
Overall Score

Rennen Recycled Sling Bag
Overall Score - 3.6/5
Style - 4
Comfort - 2
Functionality - 4
Durability - 5
Value - 3

Overall Pros

Overall Cons

Boundary Supply Rennen Sling Alternatives

Just in case you aren’t sold on the Boundary Supply Rennen Sling yet, we’ve added some alternative recommendations below. 

These recommendations are very similar to the Aer City Pack, but have some important differences that might work better for you! 👇

Alternative #1
Aer City Sling 2

Aer City Sling 2

Minimalist and comfortable

Alternative #2
Bellroy Sling

Comfortable and has a lot of color options

Alternative #3
Aer Tech Sling 2

Aer Tech Sling 2

Larger capacity and has a 

laptop compartment

Boundary Supply Rennen Sling
Gist of the Pack

Welcome to our Boundary Supply Rennen Sling review. 

Boundary Supply sent us this sling as well as the day pack, both of which are part of a new line of travel products made from eco-friendly materials. We’re going to tear this sling apart. There are some things I really like about it. And a few things I’m not crazy about. Let’s go!

This is a sling that can double as a fanny, or is it a fanny that can double as a sling? I’ve got some opinions about this coming up soon. There are currently three different color options available. You got a tan, a blue and a black. I wish they would’ve given me the tan or the blue. They gave me the black. It’s not that the black looks bad, I’m just kind of sick of black. And Boundary Supply’s tan is always so on point. This also has an XPack counterpart that’s also awesome! The capacity is three liters, which is about average for a sling. It weighs half a pound. And for the price it’s currently running about $80 U.S.

Woman wearing a Rennen Recycled Sling

For the style of the Boundary Supply Rennen sling. Style is very subjective, but I think the Boundary Supply style is usually quite cool. It’s always got like this cool, retro old school look to it, but sort of modernized and brought into the future. It’s the exact way I feel about this sling. There’s still that classic sort of adventure feel, but without feeling like outdated. And with the style too Boundary’s not too loud with their branding, they got a little stitch logo right there. Little logo on the side right here, and that’s it. Subtle yet tasteful.

The materials are probably the most important part of this sling and really all aspects of their Rennen series, because they’re super duper eco-friendly. In fact, 11 plastic bottles were melted down, recycled into yarn and used in this product. And the eco friendliness doesn’t stop just with the exterior materials. It’s the interior materials. It’s the zippers. Everything is Bluesign, which means super duper eco friendly.


Boundary Supply Rennen Sling
Front of the Pack

Important points: Minimalist, water-resistant YKK zips, and smooth overall feel on some parts

Let’s talk about the front of the sling. Minimalist branding. A really nice PU-coated YKK zip right here. Nice, smooth opening. Nice, smooth closing. The zipper pulls are comfortable and have a nice grip. We’re also having a smooth feel on this rubbery plastic part. That’s it on the front. Nothing much to say!

Boundary Supply Rennen Sling
Middle of the Pack

Important points: In the middle of the pack, we’ve got a water bottle holder, two side handles, a top pocket, and a main compartment. 

Let’s dive into the middle. Now this is where the sling or fanny or whatever you think it is, gets really fun, because I love what’s going on in the middle. Let’s go ahead and go pocket by pocket, feature by feature.

First up key ring right here. If you like a key ring or a carabiner, you just pop the keys on there. Easy to grab, perfect. We got two pockets, same size, great for something like your AirPods. I keep a spare mask in there, also eye drops. These pockets don’t expand very much. They’re actually a little tight, so you’re not going to get a bunch of stuff in there. But remember it’s a three liter sling. This is not meant to be like max capacity. This just helps you organize your little tidbits.

Rennen Recycled Sling Bag

The main compartment is a decent size, perfect spot for you to just pop your shades in there. You can fit a few other tidbits, phone. For instance checkout right now, I’m sipping on a 600 milliliter Gatorade bottle and it’s a nice snug fit. So if you are someone who carries a water bottle, which makes sense, you’re in line with the whole eco-friendly lifestyle. If it’s under 600 milliliters, it’ll be a nice snug fit. Then on the flip side, we got this pocket right here, smooth zipping experience. I just got a pen in there. I got some, some coinage. This pocket runs about three quarters. The depth of the front compartment in general.

And one other note is I love that Boundary Supply does this. The internal materials are made with a light color, like a light tan, which is nice because that helps to create a highlight effect in the sling, which makes it easier to find your gear. That’s about it. It’s a small sling. This gives you some basic organization. So if you’re just looking for a simpler sort of experience, the Boundary Supply Rennen sling will provide that for you.

Boundary Supply Rennen Sling
Back of the Pack

Important points: It has cozy shoulder straps, a well-ventilated back panel, a magnetic sternum strap, and a luggage pass-through holder.

Let’s talk about the back. First up, hidden pocket. I mean, it’s not super hidden, but it’s a really nice pocket because it’s a perfect spot for your phone. This pocket is yet again, protected with a YKK waterproof zipper. These sorts of zips are a little bit sticker yet smooth. There’s not a lot of depth to this pocket. I only recommend putting things that are flat in there. Mostly a phone. It’s basically just a phone pocket. Tab did bring up a good point though, since the sling does kind of shoot forward like this, it actually makes getting your phone even easier. Maybe that’s why they did it. I don’t think so, but it’s nice to know.

Shoulder straps of the Aer City Pack

Okay, let’s start with this shoulder strap. Here we have some hardware, see these buckles right here, Tab and I aren’t too sure about these guys. I’m want to place my trust in Boundary Supply, but I don’t know the brand. I haven’t tested it for long periods of time, so I’m going to give Boundary Supply the benefit of the doubt there. But in use, it’s fine. We’ve got some basic nylon webbing, feels durable. We’ve got a dangle stopper here, which is plastic. And then if you go into fanny mode, we’ve actually got a second dangle stopper right here. So you go ahead slide the excess nylon through and then bam. It just kind of helps us make the bag a little more seamless and less dangley. Then boom, when you’re in Fanny mode, you can just pop these guys there on both sides. It works.

Boundary Supply Rennen Sling
Pros and Cons (Detailed)

All right, let’s wrap this review up by going over the overall pros and cons. Overall pro number one is got to be the materials, they’re recycled yet premium. 

I’m in love with Boundary Supply’s mission of sustainability. Pro number two is going to be the organization because it’s actually quite nice. It’s not too much. Some people are going to think that the AER slings are overkill with their pockets. You got your three pockets here, pocket there. That’s it. Nice little balance. And pro number three is the overall Boundary Supply look and specifically the color options. You’re not limited to just black on black with this guy. The blue looks great and the tan looks amazing.

But cons. Con number one is going to be pretty obvious, it’s like I just don’t know exactly what this guy is. It feels like a fanny, but it’s being advertised as a sling. It seems to be this weird little middle ground between the two, but yet it doesn’t work as either perfectly. So you get both, which is nice, like the AER sling, you’re not going to be able to wear as a fanny. Impossible. This guy though, you can go from fanny to sling and it’s not perfect at either, but you do get both. And then specifically with that con number two I’ll say is just that lack of a fit on the torso when it’s being worn as a sling, which just kind of makes it feel not uncomfortable, but awkward.

Boundary Supply Rennen Sling
Alternatives (Detailed)

So let’s talk about who I think the Boundary Supply Rennen sling is for and who it’s not for. 

This sling is absolutely 100% for you if you want to buy gear made by companies who are committed to sustainability. Sustainability. If that’s more important to you than necessarily the comfort or the features, and you just are really passionate about eco-friendly materials, this is the sling for you. This is also the sling/fanny for you if that’s what you’re looking for, a sling/fanny. Remember it’s not perfect at either, but it does do both. 

But let’s talk about who this sling/fanny thing is not for. This sling is not for you if you’re looking for a sling that fits sort of perfectly on your torso. As I highlighted, it’s a little bit of an awkward fit. On the pro side that means you get the fanny/sling experience. But if you’re just looking for a sling that just perfectly, just like that. This isn’t the guy. If that sounds like you, please check the links below, we got some sweet ass sling reviews down there. This is also not the sling for you if you carry a bit more stuff. This is only three liters. It’s a good size for a sling, but sometimes it’s just not big enough. If you need something a bit larger, like six liters or 10 liters, take a look at the links below. We got some larger sling reviews down there.

Boundary Supply Rennen Sling

What do you think about the Aer City Pack? Is the access to the main compartment a little too limited? Do you wish that the water bottle holder could hold a girthier water bottle? Love that word. Or if you own this pack, please let us know what your experience has been like so far. We would love to hear from you, and your comments help make the internet and this channel just a better place, more educated, which means that people can find the pack that is perfect for them.

Thanks, guys, and we’ll see you next time!

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