This 'envelope' allows Kindle use in environments that I would not normally wish to take my Kindle near, eg: damp/humid/rainy places or even on the beach.
The bag has a padded back to protect the Kindle on rough surfaces, and the front is a thick clear plastic. The back and front are welded together with about 2-3 mm seam, that should not come apart in general use. The opening is protected with two sturdy plastic-lock seams (eg like those on freezer bags), that fold over twice to help keep water and particles out even more. The folded over opening is then kept in place with a guard that is kept in place with two pop-studs.
The bag comes with its own bag(!), and a carrying strap, that looks rather flimsey, but is made in strong plastic and does not look as though it will break easily.
The buttons are easy to operate; turning on is easy enough once you have learnt the technique. To turn it on, rather than holding the Kindle and trying to move the switch, it is easier to move the Kindkle inside the bag whilst using your thumb to keep the switch still (I think you just have to try this one out!).
The bag does not seem to distort music or text to speech and does not attenuate the sound.
I'm pleased with this accessory and have used it to keep my Kindle dry and it works well. (Not quite so sure that I like the logo TrendyDigital right on the front!! But I'm more interested in functionality rather than looks this time).