PROFORCE Forearm Guard, Black (Medium)

do i get one or two guards when i by it?

is there a hard shell? or is it all fabric and cushioning? i want something that will protect from heavy blows and even knives.

The medium size, how long is it?

Will this cover my previously fractured ulna? Is the padding on the side or would i have to wear it sideways in order to cover the bone?