Head Markings On Bolts
![head-markings-on-bolts head markings on bolts](https://www.innovation-creativity.com/wp-content/uploads/2021/01/head-markings-on-bolts.jpg)
Head markings on bolts that require cotter pins. With a notch in the same plane as the hole, even working blind you could slip the pin in with ease.
By G.Wilson, N.Guilford, Conn.
June 1959
You can purchase various bolts on Amazon…