[MultipleParadox]

There's protector made of tempered glass now
I just ordered one from techarmor, check spiggen a brand as well

I reckon it's made of gorilla glass, same as iPhone's 5/5s screen (not sure if the 4/4s have that same glass, anyways)

Saw a promo vid (to take with a grain of salt) where they drop a 1inch steel bearing from 1 foot or so on the glass/phone with no damage; seems convincing

So that might be your best bet