It's a 1/2" bolt with a washer between the leg and beam.
Snug and double nut.
Both the leg and head are appx. 2.5 x 4" Ash with the head half-lapped onto the leg. Oak will work as well. There is also a bolt sticking out of the bottom of the leg to act as a foot peddle. There is a small v-groove in the beam to which the head presses against to hold the square pc. on a 45 deg. while it is also able to straddle the groove when squaring.
