I had been looking for something like this for a very long time, when I saw this on Amazon. But I was put off by the first reviewer who claimed that it was not flexible and did not mould itself to the keys and was therefore no better than a sheet of cardboard. However, I went ahead and purchased one for myself - and I can assure you that her comments are completely UNTRUE! But unfortunately, the supplier does not give clear enough instructions and because of this, I also thought it was very stiff at first. But upon reading one of their other listings, I discovered that you have to remove the backing sheet first! And once you have done this, you are left with an extremely flexible, fine sheet of silicone, which sits comfortably over the keys and allows you to type ALMOST as well as usual! I say almost as well because it did make me miss a few characters at first. But once I got used to the SLIGHTLY heavier pressure that you have to use, it was fine!
The reason I particularly wanted to try one of these keyboard covers is because the lettering always wears away extremely quickly on all my keyboards, which apparently is mainly caused by certain chemicals that may be present in your body and NOT by too much pressure being applied as I first imagined! And since these covers prevent those bodily chemicals from coming into direct contact with the keys, they should prevent the lettering wearing away so quickly. So when I get my next new keyboard, I will use it with one of these covers from day one, to see if the lettering lasts any longer! I will then report back with my findings although I am fairly confident that it will do the trick.