Most screen protectors are just a thin layer of flexible plastic that do an adequate job at shrugging off scratches. But they're no where near as tough as Spigen's new GLAS.t which adds another layer of glass for maximum protection.
At just 0.4mm thick the chemically treated tempered glass adds minimal thickness to your iPhone 4 or 4S, and doesn't affect its touchscreen functionality. It's also three times harder than plastic, easily surviving an attack from scissors or a box cutter. And because it's tempered, if you do succeed in shattering the GLASS.t protector it will break into thousands of little pieces, instead of a handfull of sharp glass daggers.
As someone who's applied countless screen protectors in the past, seeing how easy the installation process is blows my mind. It literally looks like it applies itself without a single bubble. Well worth the £18-odd plus shipping, which is what a good plastic protector will cost you anyways. [Spigen via iLounge]