From the Paravel website (https://tourparavel.com/products/fold-up-belt-bag):

Our Fold-Up Belt Bag is an everyday bag with a not-so-everyday detail—it folds up flat and zips into a barely-there pouch, then expands in a blink of an eye. Perfect for strolls, bike rides, and unexpected excursions, it's ultra-lightweight and sustainably crafted from our Negative Nylon. Sling it over your shoulder, wear it as a crossbody, or buckle it around your waist for the ultimate hands-free experience.


Dimensions:

Length x Height x Width: Unfolded 8" x 5" x 2" (20.3cm x 12.7cm x 5.1cm) Folded 3.75" x 5" x 1" (9.5cm x 12.7cm x 2.5cm) 
Strap Length: 21"-34" (53.3cm-86.4cm) 
Weight: .31lbs