skip the dollar tree ones. They are cheap, but man.. its a throwaway item.
The things are basically like a trashbag over your body with a super huge "cap" for your head. If you are larger or want some mobility with your legs/arms, its not for you. the cap is too big and keeps coming off.
Super huge for a child. my 5yo we used once and the head opening came to her mid chest. she had to hold the bottom of the opening so water wouldn't get in.
I bought a rain coat/poncho in pink for her at
walmart for a few $. hopefully it lasts.