I have had one of these for many years now, and it is still in use. I bought it from my local Boots the Chemist, and I must say it has done sterling service. The instrument works very simply, it is very much like a piece of cine film, and is treated so it reacts to different temps, when reacting, it shows up some numbers, which are made to corespond the temperature at which it changes. I hope you are following this. The numbers can be easily read, and require nothing more from the patient than just lying there. There is nothing to be forced into the mouth, or any other orifice for that matter, the whole operation is painless, I have even checked temperatures while the kids were asleep.
I can not remember how much the item cost, but it was a real bargain, and comes in a handy llittle case, which stops it from getting lost. There is no need for any maintenance, just a wipe over when it needs it. I can just imagine this still working in ten years time ot even longer, and in theory there is no reason why not. I would like to say this is very accurate, and it is usually 98.4 on myself, as I check it before use. I have to say I have no real exact way of proving it is accurate at higher temps, but have no reason to doubt it.
I am sure these are still on sale, and must recommend them to you all.