Most listings describe the masks as made from plastic; at least one listing notes polyester. The specific type or rigidity of the plastic is not specified in those listings.
Dimensions vary by listing. Common examples are about 7.0" (H) x 7.0" (W), 8.0" x 8.0", and up to roughly 8.4" (H) x 9.6" (W).
Most listings describe the masks as one-size-fits-most and indicate a maximum head size of about 24 inches (head circumference). Check the listing measurement against your own head size for best fit.
The listings recommend the masks for ages 14 years and up.
None of the listings require or use batteries — the masks are unpowered.
Product descriptions characterize the masks as lightweight and designed for party use and play, suggesting they aim for comfort. If comfort details matter, check the listing for padding or strap information.