Briefs Trial Pack - Flat Seams

This listing is for the Find My Size WunderUndies Breifs Trial Pack with flat seams.

We have found that while kids love their WunderUndies, they are very particular about their sizing. Some like them looser and some like them tighter. So the Find My Size Trial Pack was invented! With this trial pack you will receive 2 pairs of WunderUndies briefs in 2 different sizes. This way you can find the size that suits your child the best. 

WunderUndies briefs are the ultimate solution for sensory-sensitive kiddos—or for any parent whose child hates to wear underwear. Designed with care, these briefs are crafted from incredibly soft, eco-friendly bamboo fabric that feels like a second skin. Say goodbye to irritation and discomfort—WunderUndies are elastic-free, featuring a fabric waistband that stays comfortably snug without pinching or slipping.

What makes these briefs truly special is their flat-seam construction, meticulously crafted with a flat lock machine. Waistbands and leg bands have their seams on the outside and are sewn flat, ensuring a smooth, irritation-free experience. Paired with a tagless design, these briefs are a game-changer for kids who struggle with traditional underwear.

Once your child tries WunderUndies, they’ll finally have underwear they love—and so will you.

Available in sizes 2T–12.

Some people see bamboo fabric and worry that it will be hard to care for. It's not! Many customers have praised the durability of WunderUndies. Here's what you need to know:

Machine wash cold with mild detergent. No fabric softener. Dry on low. If you feel the need to iron your undies, do that on low too. These are the practices for the longest lasting undies.

Our fabric blend of 67% bamboo, 28% cotton, and 5% spandex is crafted to provide unmatched comfort, durability, and versatility. Bamboo offers exceptional softness, breathability, and moisture-wicking properties, making it perfect for sensitive skin and active kids. Cotton adds strength and structure, ensuring long-lasting wear, while the addition of spandex delivers just the right amount of stretch for a snug, flexible fit. This thoughtful combination creates underwear that feels gentle, moves effortlessly, and stands up to everyday play, all while supporting sensory-friendly comfort.

With WunderUndies first round of boxers, it quickly became clear that they ran small. So with the next round we made some needed changes. They are:
1. We shifted everything one size. Our old size 12s are now size 10s and so on and so forth.
2. We enlarged the waistbands ever so slightly. 

If you have bought from us before and are worried about what size might fit your child now, you are welcome to get another trial pack. But if you are new to WunderUndies we believe that the size chart above now more accurately reflects the best fit for our Flat Seam undies. If you are buying Soft Seam Undies, consider sizing up. 

Additionally, our flat seam briefs are slightly larger than the soft seam version.

As always, we highly recommend getting a trial pack first.