I own this envelope now for over 3 years, so that I can give an informed assessment. In short, the shell is very good. It's amazing that even after all this time and really daily, intensive use absolutely no wear can be recognized by material. Therefore, with respect to material quality before a 1. Also good is that it is just not a hardcover, but is made of rubber. The impact resistance is after all - so for a relatively thin shell - increased to such an extent that the cell phone does not break from a typical height of 1.5 m, when it falls down. This happened to me several times and my iphone siet still like new. To summarize: highly recommended (like many other cases of mumbi also)