So simple and yet probably the most popular design of centre finder found in the world!
Woodturners use it to find the centre of workpieces to turn but of course, it can be used to find centre on any square, round, hexagonal or octagonal stock up to 8in (203mm) square or round.
This comes from the factory in Taiwan that’s been making it for decades and it is produced from durable, high quality bright yellow transparent plastic for improved visibility.