A boxer brief with a sewn in front pocket that holds a frozen gel pack. Unlike a bag of ice, it stays in place.
| Size | Waist |
|---|---|
| S | 28 to 30″ (71 to 76 cm) |
| M | 31 to 33″ (79 to 84 cm) |
| L | 34 to 36″ (86 to 91 cm) |
True to size. Between sizes? Size up. The fit is snug to keep the pack in place.
Unworn kits return free within 30 days. If you wear it in a real session and the fit is wrong or the cooling does not do what we said, email support@koldwr.com within 30 days and we will refund it. You do not need to mail worn underwear back to us.
Full terms
Built for the sauna. It works anywhere you sit still in dry heat, but the sauna is what we designed it around and the sauna is what we test it in. Read what the research actually found.
Source: Garolla A, et al. "Seminal and molecular evidence that sauna exposure affects human spermatogenesis." Human Reproduction, 2013. Read the summary →
In every box
Nothing else to buy. Open the box, freeze the packs, and you are set for your next session.
Engineered performance knit: 92% modal, 8% elastane. Built to wick fast, dry fast, and keep its compression with a loaded pack, wash after wash.
The pouch is double layered so it carries the weight of a frozen KoldPak without sagging.
A BPA free cooling gel pack, shaped to sit flat in the pouch rather than slide around. Two come in every kit so one can freeze while the other is on you.
KOLDWR is a comfort and wellness product, not a medical device.
Four things that make it work in a hot room.
01
Every kit comes with two KoldPaks. One on you, one in the freezer. You are never waiting on cold.
02
Double layer construction holds a frozen KoldPak in place while you move, sit and sweat.
03
Wicks, dries fast, and keeps its compression through hot rooms and cold plunges.
04
Every batch is small on purpose. If something is not right it gets fixed in the next run instead of sitting in a warehouse.
Every one of these is a real thing sauna users do. Here is honestly how they compare.
A boxer brief with a sewn in front pocket sized for a frozen gel pack. Two packs come in the kit, so you can swap a fresh one in. The brief is a 92% modal / 8% elastane performance fabric.
That is the whole product. No electronics, no battery, nothing to charge, nothing to subscribe to.
A sauna raises your core temperature. The area in the front of your shorts normally sits a couple of degrees below core temperature, and it does that for a reason. The pocket holds a frozen pack in constant contact at that spot, so it stays cooler than bare skin would while the rest of you takes the full heat.
The mechanism is not clever. The useful part is that the pack stays where you put it instead of sliding off your lap.
Freeze both gel packs for at least 2 hours, slide one into the built in pocket, and go. After your session, rinse the packs and refreeze for next time.
We have not run a laboratory test of pack duration at sauna temperature, so we do not publish a number. We would rather have that gap on the page than a figure we made up.
What we can describe: the pack cools hard while it is frozen, and once it thaws it keeps insulating, so the area stays cooler than bare skin for the rest of the session. Two packs ship in the kit so you can swap a fresh one in for another round.
One KOLDWR Pro boxer brief with an integrated front cooling pocket and two reusable BPA free cooling gel packs.
True to size. If you're between sizes, size up. The fit is snug to keep the gel pack securely in place.
| Size | Waist |
|---|---|
| S | 28 to 30″ (71 to 76 cm) |
| M | 31 to 33″ (79 to 84 cm) |
| L | 34 to 36″ (86 to 91 cm) |
Not yet. They are not in production. Tell us your waist size using the form above and we will let you know the moment they are.
Snug, deliberately. The pocket only works if it holds the pack in position when you sit down, and a loose brief lets the pack shift. If you are between sizes, size up.
Yes. With the pocket empty it is a performance boxer brief and reads as one. Plenty of people wear it to the gym and put the pack in only for the sauna.
The packs cool gradually rather than shocking you, and the pocket keeps a layer of fabric between the pack and your skin, which is the main reason the pocket exists instead of us just selling you a pack.
The first thirty seconds are cold. After that most people stop noticing it, though we will not pretend that is a tested figure. It is what our first customers have told us.
It should not. The pack never touches bare skin; the pocket fabric sits between. But treat it like any cold pack: do not take the pack out and press it directly against skin, do not fall asleep in it, and if anything feels numb or painful rather than cold, take it out.
Cold applied to that area is not exotic. The design point is that the pack sits in a fabric pocket rather than against bare skin.
That said, we are an underwear company and not a clinic. If you have a circulatory or nerve condition, reduced sensation, or you are recovering from surgery in that area, ask your doctor before using it.
A sealed, BPA free cooling gel built for repeated freeze and use cycles. Do not microwave them and do not puncture them.
Behind the problem, yes, and it is not controversial: multiple peer reviewed studies show that elevated scrotal temperature measurably affects sperm count and motility, that the effect tracks with cumulative heat exposure, and that it is reversible.
Behind this specific garment, no. Nobody has run a clinical trial on KOLDWR. What we can tell you is what it does mechanically. It holds a cold pack in position at the place the research points to, and we let you draw your own conclusion from there. Read what the studies actually found.
No, and we are not going to say it does.
What is established is the problem, not our solution to it: regular sauna use is linked to measurable reductions in sperm count and motility, the effect scales with cumulative heat exposure, and it reverses. KOLDWR reduces heat exposure at the one place that research points to. Nobody has tested what this garment does to anyone's sperm count, fertility, or chance of conceiving, so we make no claim about any of it.
If you are trying to conceive, talk to a doctor. Not to an underwear company.
No. We have never claimed it and we are not going to. Nothing we sell has been tested for any effect on hormone levels.
This is a question about your body rather than about our product, so here is the physiology and nothing more.
Sperm takes roughly 64 to 72 days to develop, plus around another two weeks in transit. A sample taken today largely reflects conditions from two to three months ago. Anyone selling you something that promises a change in weeks does not understand that timeline.
We are not telling you KOLDWR will change a result, because we have not tested that. We are telling you that if you change anything at all about heat exposure, this is the clock you are on.
If your doctor has told you to stop, stop. That is the more conservative option and we are not going to argue you out of it.
This product exists for the person who has read the research, does not want to give up the sauna, and would rather reduce heat exposure than quit the habit. It is a compromise. We would rather describe it as one than pretend otherwise.
No. A frozen gel pack in hot water is a warm gel pack within minutes. It does nothing for you, and we would rather say so than take the order.
You can, but you do not need to. In a plunge you are already cold everywhere, so the pack adds nothing while you are in it.
What the plunge does do is chill the pack again. If you are doing contrast rounds, that means you go back into the sauna with a cold pack rather than a spent one.
Yes. Steam is humid rather than dry, but the pack behaves the same way. It is in a pocket against your body, not submerged. The sauna is what we designed it around and what we test it in, which is why we lead with that.
Yes, anywhere you are sitting still and it is hot: hot yoga, a long drive in summer, a heated seat, a hot shop floor.
The sauna is the use case we built it for and the one we understand best, so that is what the product is designed around.
Yes. Remove the gel pack, machine wash cold, hang dry. The gel packs just need a quick rinse between uses.
They are built for repeated freeze and use cycles. Refreeze after each session. We have not put a cycle count on them because we have not tested one to failure.
An insulated bag with ice works fine for the trip. If your gym or studio has a freezer, ask. Most will let you drop a pack in for the twenty minutes before your session.
No. The kit comes with two: one for the pocket and one in reserve to swap in mid session. Replacement packs will be sold separately.
Two kits in one order ship in one mailer and get packed once. Two kits ordered separately are two mailers, two pick fees and two postage labels, which costs us roughly eight dollars more to fulfil. We pass that difference back instead of keeping it.
The other reason is laundry. A kit in the wash is a session you do without one.
It ships in a plain bubble mailer. Inside, the kit is in a printed box that says KOLDWR Cooling Boxer Kit and lists what is in it: one boxer brief, two gel packs.
Nothing on the mailer or the box says anything about why you might be buying it.
Nothing is shipping right now. There is a problem with this production run, so the kit is off sale while it is remade.
Join the waitlist on the product page and we will email you as soon as the next run lands. We are not putting a date on it until the stock is in the warehouse.
To some countries. US shipping is free. Canada, the UAE, Australia, New Zealand, Switzerland and Singapore ship at a flat $25 tracked rate, duties paid on delivery. Join the email list and we will tell you when yours opens up.
Two things cover you.
Standard returns: unworn kits go back free within 30 days of delivery for a full refund.
The First Sauna Session Guarantee: use your first kit in a real session, and if the fit is wrong or the cooling does not do what we said it would, email support@koldwr.com within 30 days and we will refund it. You do not need to mail worn underwear back to us. Full terms.