Having purchased two was surprised to find these have an expiry date (so second one unusable) First one was faulty however was replaced with another one date expired within a month! I phoned re replacement but was told will not replace as over two weeks use before not working. Due to high cost of these feel users need to be aware. Seems an expensive luxury with high failure rate, have others had problems.?
Thanks for pointing that out, I purchased two at the end of April and they're OK until 31st July. I shall definitely make a note because I would hope for at least a 3 month window in which to use them. They are expensive as you say, so I'm not using them constantly, only when I'm changing diet and/or medication.