My 1st belt stopped working within the warranty period, and they immediately sent a replacement. Unfortunately, the replacement stopped working, and I thought I was screwed, but AGAIN, they are sending a replacement, as it, too, is within IT'S warranty period. That feels unheard of. I also got a "lemon," of a battery pack that doesn't hold a charge - yet again, no questions asked, replacement on the way. I tend to wonder if the product is inherently flawed, but it wouldn't matter, as they keep sending replacements! And they are kind and rapid in their response!