Quite a simple ingenious system. Well designed and I particularly like the vent/drain built into the bags just below the snap shut line. I did at first think there was a tear in the bag (teaches me to read instructions properly). A word of caution however .. Although it does tell you in the instructions that some clear materials might become opaque through repeated steaming, I still wasn't prepared for one of the favourite little transparent cups to be made opaque after just the first sterilisation in one of these bags. So if you have any items which you want to continue looking pristine, my advice is don't put them in the bag. Just wash them with antibacterial washing up, or stick the in your dishwasher if you have one, or put them in a larger container and soak them in just boiled water from the kettle. The idea of a snap shut sterilisation bag is a good one, but certainly not universal, because also one of the plastic handled items also came out slightly misshapen, since the steaming in the microwave does superheat everything. Unless you are an expert in what materials your stuff is made of, and know their tolerance to heat, then it will take some trial and error. The instructions are not comprehensive as to the full list of materials that won't tolerate the process.
Don't forget also - don't put anything with even a tiny bit of metal in. It is a microwave process after all!