BolesiNylon Bicep Bands Compatible with Whoop 4.0 Fitness&Activity Tracker,Soft Stretchy Breathable Fabric Elastic Washable Adjustable Sports Loop Bicep Strap for Women Men.OEKO-TEX STANDARD 100

While the material seems nice and is certainly stretchy enough, these bands are very thin and have a very minimal width. I believe mine was shipped without a key piece that holds the clasp down. Regardless, I was disappointed with the packaging, missing piece and thinness of this item. I would not purchase this again

Works perfectly. I have zero issues using this when running. When I'm done, I transfer the Whoop back to my wrist band. I use it with a Whoop 4 to 5 adapter so it's not perfect, but it works. Most other bands don't include the metal bracket, so it was nice to see it included.

Can't recommend it because of one fatal flaw... the metal grooves that hold the fabric strap in place aren't deep enough, so no matter how tight it is it seems to flop over in my sleep.In the photo the green is factory Whoop, and the blue line shows the shorter rails of this one.(quality seems great otherwise - tragic)