Guess This Tool, Win a Tool #6

Tell us what this is, win a Stanley FatMax level

Guess This Tool #6
What is this?Vin Marshall

All right, smarty pantses, give this one a go. Lately, you brilliant DIYers have been making short work of our Guess This Tool contest, so we're going to mix it up a little and see if we can't stump you for more than 10 minutes. This is a tool of sorts, but it's in the early stages of a PopSci Dissection. As usual, the first and most precise answer in the comments will win something from our friends at Stanley: a FatMax 24-inch level. Good luck.