The recipient does not wear "flip-flops" but we moved into a house with white carpet. It rubbed my toe in a way that felt like Id get a blister. I ve done that , too. For $25 spent on a charger, you would think a proper cable or very least an adapter would be included ! Cant wait to wear them in the wet weather. Customer service matters! MH7513. It was much cheaper than this version. I am very satisfied and I would definitely recommend these. Its not perfect, though.