Excellent value screen protectors for the Samsung Galaxy S3 and a real bargain at the price. If you follow the instructions carefully it fits perfectly and makes almost no difference to viewing or operating the touch screen. The pack contains 10 sheets plus 10 microfibre wipes for ensuring good cleanliness and adhesion. For best results I'd suggest first cleaning any grease from the glass with a cloth dampened with some soapy water, followed by a wipe dry with the microfibre wipe. (Warning: I do mean just damp! - don't overdo the water! The S3 is packed with water sensor "tell-tales" which change colour to let the Samsung service centre know if your phone has got wet inside, invalidating any warranty.)
10 sheets is enough to last for years if you're reasonably careful. Also it gives you some leeway to make a mistake or two. It's very easy to get specks of dust under a screen protector if you're careless when fitting. Also I suggest you first offer up a protector to the screen with the protective backing still on it to see exactly where it sits - note the cutaways for the front camera and sensors. If you align it badly, you really have to abandon that try and use another sheet. Once you've placed it you can't take it off and put it on again.
I did see an earlier review that the protector didn't extend fully to the edges of the phone. They don't, and there's a good reason for this. As you get near the edge, the flat front surface starts to curve away towards the side frame, and so the protector is designed to stop short of this. If it was any bigger, the edges would soon lift up and start to pick up dust and dirt and have to be replaced.