Bests & Worsts Reviews from Amazon

I bought this about 3 months ago to put on two Roombas that would get lost under furniture, etc. It worked fairly well at first, although one of the set would go off randomly on its own at night (I ditched that one and used one of the others). They work very poorly now; I've tried changing batteries with no luck. UPDATE: I should add that the company read this review and sent me a set of replacement tags. In the meantime, I'd switched to a different system that seems to work fine, so I haven't tried the new ones, but it is certainly impressive to me that the company read these reviews and responded. On that basis, I would increase the rating if I could.