This actually works. You can fill the bag up and the straps keep it compressed. Able to cram a lot more into the suitcase.

Son una excelente opcion para reducir el tamaño de la ropa. Muy efectivas.

Works as described helps condenses my camping / military gear.

Sea to Summit Dry Bag ReviewI recently tested the Sea to Summit eVac Ultra-Lightweight Compression Dry Bag (20-liter model), designed for outdoor enthusiasts seeking both dryness and efficiency.While the primary function of the eVac is to keep contents dry, its usability extends beyond mere waterproofing. It has a sturdy grab handle and versatile attachment points that make it convenient to carry or secure to other gear. Additionally, the transparent window allows for easy identification of contents without having to rummage through the bag.Excellent waterproof performanceLightweight & durable constructionInnovative eVent® base for easy compressionUseful features like attachment points and grab handleMade well with quality materials.

*Update. I originally wrote this review in mid May of 2023. But a technical issue prevented this review from being posted for over a month. In that time I've used the compression/dry bag on a few outdoor contracts and have been very happy with it. I've been primarily using it to store all my clothing for the contract and I still usually have a lot of room to spare. It's not as organized as what I was doing previously (packing cubes) but it's more compact and if I'm feeling lazy I could just leave the sack in my vestibule (or outside it if I'm uncharacteristically extraordinarily lazy) without repacking into my main bag and not worry about the elements getting my clothes wet. My review for the heavy duty sack isn't up yet but I'll just spoil it and say I've been really happy with it despite its significant increase in weight and my choice to go 8L. The Ultra-Sil review also hasn't been posted yet but I can again say that it performed quite well.**Original review*I was incredibly fortunate to get the chance to review 3 Sea to Summit dry bags. This, Evac Compression Dry Bag UL (Ultralight), the Evac Compression Dry Bag HD (Heavy Duty), and the Ultra-Sil Dry Bag in the colors and volume of my choice. I was also offered an opportunity to review the new Big River but declined. So I have a great opportunity to compare and contrast the different dry bags. Something that is especially important for the Evac bags which are available in several different fabric weight configurations.For the Evac Compression Dry Bag UL I opted to go with the 20L. I was offered the chance to review the HD version first and I was a bit too overly conservative when it came to volume (8L), something I regretted immediately (it still does exactly what I wanted it to do it just would have been nice to have the extra space of the 13L). So when the UL came up, I decided to size up significantly. 20L is a good all around size that gives you a lot more space options without being an excessive amount of space if you only have a few items.Remember this is not only a dry bag, but a compression sack. So if you have a very specific set up equipment you plan on storing in these dry bags my recommendation is to go up a size. Between the compression straps and the roll top you can always fold/compress away any excess (vertical) space but you can't add any new storage space.There are three compression bags in the Evac line, and a fourth Evac dry bag without any compression. The three bags represent three different fabric weights and abrasion resistance levels. The UL utilizes Ultra-Sil 30D Cordura nylon, the regular Evac uses 70D, and the HD steps things up considerably with 420D. The ultralight may use the lightest and least abrasion resistant fabric of the line, but that doesn't mean it's tissue paper fragile. Quite the contrary. For comparison, Enlightened Equipment offers a 20D as the maximum possible weight and abrasion resistance fabric for their commercial line. Enlighten Equipment's heavy duty professional and defense focused line uses a very similar but not quite the same 30D as its outer fabric to excellent effect. It's my opinion that Sea to Summit's 30D fabric provides an excellent durability to weight ratio. That said, if you plan on overloading it and then repeatedly and purposely whacking it against sharp rocks, eventually it will tear. But I feel confident in saying that its durability is more than adequate for the vast majority of end users. It's also the same fabric used on the Ultra-Sil Dry Bag line. The Ultra-Sil refers to the silky finish of the fabric that's reminiscent of synthetic sleeping bags. The idea is it makes for a very slippery surface that slides easily in and out of packs. The surface is indeed slippery, and does glide nicely around other dry bags and in packs but if you're worried about it being so slippery that you'll drop it don't. Between the grab handles, straps, and the fabric on the top and bottom pieces there's plenty for you to hold on to.The Evac system with its eVent fabric is what caught my eye with these bags and is the star of the show. Instead of relying on a one way purge valve of some sort, the Evac bags use a special fabric on the bag base that allows air to escape but doesn't allow for water and moisture to enter. So it allows you to compress contents down to a greater level than what's normally possible with a dry bag because air will be expelled as you cinch the straps down. It's important to note that while this feature works great, it's subtle. Don't expect air to escape as quickly as it would if you have a big open purge valve. You still need to make sure there isn't a ton of air trapped into the bag when you're closing the roll top. It's more than it helps push out that last bit of air that always gets trapped in your dry sacks when you're closing them up.The bag closes up like any typical roll top. But if you're confused or unfamiliar with the mechanism, there is a big instruction tag sewn into the bag (you have the option to cut it out) that gives instructions in multiple languages. With diagrams. So if you're still confused, that's on you. Sea to Summit makes a point of emphasizing that the buckle used to close the dry bag is field replaceable. Which is good. Field replaceable hardware is something I'm particular about and is unfortunately not as common as it should be on the recreational and commercial side of the outdoor industry. Meanwhile it's a standard feature across the board for equipment catering to the tactical and defense side of the outdoor industry. Alas, Sea to Summit's approach to field repair is typical of the rec world. Proprietary buckles. That they will happily sell to you for six times the cost of a typical repair buckle. In all fairness too Sea to Summit, it is a well-designed buckle that uses a Philips head pin for installation and removal. I just think it was unnecessary to reinvent the wheel. If you do want to replace your buckles or you want to have an extra on hand for the main roll top you want the 15 mm, 2 pin,Side Release Field Repair Buckle.The compression is also typical. With a top cover that comes over the roll top with four compression straps on the corners. You have a generous amount of strap to work with in cases where you need to overload. The front two straps have side release buckles, back to just use ladder locks. Which means unless you purposely unthread the straps from the ladder locks you will never lose the top. The straps are my biggest gripe with the design which says a lot about the quality of the bag because it's fairly minor. When you compress down the contents you'll have a decent amount of leftover strap just dangling around. There is no built-in strap retention system. Given the price point of this dry bag I don't think it's unreasonable for them to include something as simple as a few elastic strap keepers. So you will need to provide your own. In my case I just took some 3/32" shock cord and set up something roughly comparable to the strap retention system found on the First Spear Multi-Purpose Pack. The MPP is my gold standard for strap retention. The plastic hardware used on the compression system are not the field repairable versions. But in the unlikely possibility that they do break you can replace the buckles with a 15 mm, 1 pin Side Release Field Repair Buckle. If the ladder lock fails, you can use the Ladder Lock Field Repair Buckle but this replacement will be suboptimal because of the way that the original ladder lock is attached to the bag. The 4 straps and lid design allow for a nice even compression. As long as the bag isn't filled to the brim with air and you're not violently cinching down the straps air will pass through the eVent fabric on the bottom of the bag naturally as you gradually cinch down the contents.Overall I've been extremely happy with this combination dry bag and compression sack. I've been using it to store my Defense Mechanisms (AKA Enlightened Equipment) pants and jacket which is approximately 7 loosely compressed (hence why I got the 8L version of the HD) and a First Spear Wind Cheater. Which still leaves me plenty of room for any other layers I might want to supplement my layering system with. Well still maintaining the looser compression I prefer for extending the longevity of synthetic insulation. 20L, even lightly filled and compressed down is too big to neatly store inside my work pack or secured on the beaver tail. But it is quite nice for stashing equipment without having to worry about increment weather and it will of course fit easily within my larger multi-day bag.As a final bit of housekeeping, if you're unfamiliar with these kinds of dry bags note that they're not designed for submersion in water. Something that is noted repeatedly in the bag documentation and in the instruction tag. There's a huge difference between submersion in water vs a downpour. If you need a bag that can survive some immersion this is not the bag for you and you need something a lot more specialized and you will lose out on a lot of the nice features of this bag.I highly recommend.