bullet "resistant" glass, its not actually glass though, is multiple sheets of a tough clear polymer laminated to promote strength and the layers provide a catch system for the rounds that hit. same principle as a bulletproof vest using dozens of layers of kevlar.
the multiple laminated layers also prevent explosive shattering like normal untreated glass. the weight comes from the dozens of polymer layers being bonded into one. its also extremely tough to cut, its stops bullets afterall, and is usually a specialised job. for example you dont cut kevlar with normal scissors you use ceramic so a glass cutter isnt going to work on ballistic grade glass.
i know how heavy it is and tough it is as i have had to work with explosives at close proximity and a sheet of ballistic glass stopped our heads, or faces at a minimum, from getting blown off if something went wrong while attatching the explosives. if you knock on it like you knock on a regular window you can feel the difference on your knuckle.
cheaper using normal glass IMO. i have heard of people using bullet resistant glass for a type of marine shrimp as a precaution though. something about it using its claw as a fist or something. how true i dont know cos i dont do marine.
