Answer:
When I type I tap these on the keys
Used to keep prisoners silent and to make temporary repairs on cars.
I occur twice in eternity. And I'm always within sight.
In many hallways you would stand, if not with this in hand.
Which weighs more? A pound of iron or a pound of feathers?
If itβs information you seek, come and see me. If itβs pairs of letters you need, I have consecutively three. What am I?