BoltSize-It - فاحص البراغي

I've spilled grease all over mine twice now and it just wipes clean, no warping or staining. It's light enough that I forget it's in my shirt pocket until I need to match a bolt.

Finally a screw checker that doesn't feel like it'll snap in my back pocket—the plastic's got some real heft to it. Slips right into my shirt pocket and I've wiped it down with brake cleaner a few times without any warping.

Spilled some motor oil on this checker and it wiped clean without a mark—the chemical resistance is exactly as advertised. Slides right into my shirt pocket, too, so I always have it handy on the job.