It is a cover for a bicycle. The picture here does not do it justice - that is the bag for putting the cover in, not the actual product.
There are three velcro straps to do, which are fiddly. If I don't do them up, I've noticed that my bike is more likely to fall over. Not sure why - maybe the wind catches it. Sorted that out now I have a bike stand. Not sure how long the will last before it rips, though.
The material is very much like tent or umberella material. It keeps things dry as long as nothing is touching it. When you put this on, the handle bars and seat will touch the cover, and thus will be damp. It keeps the majority of it off. And the silver reflective colour means that UV damage will be kept to a minimum. I like it.
Oh, and it fits my mountain bike fine - with a little room to spare, so I imagine it would be suitable for most size bikes. I am happy with this, and would recommend it.