This is sold by ENCO.
It can verify which thread a nut or bolt is (metric, inch, male, female) quickly.
The sizes are printed on each slug, and they are permanently attached by steel cable, but they slide and swivel easy to give you plenty of room if the hole is hard to get to.
It can verify which thread a nut or bolt is (metric, inch, male, female) quickly.
The sizes are printed on each slug, and they are permanently attached by steel cable, but they slide and swivel easy to give you plenty of room if the hole is hard to get to.