Ok.
The rules are: you have to know what it is to post the challenge.
The one who posts the correct guess gets to go next with
their own Whatz It? challenge.
....actually, anythings allowed... 
Without further ado... LETS PLAY!!!
This is a pneumatic tool measuring just under 6” total length.
(this one should be easy)
Whatz It and Whatz It for?