What are the specifications of the bolts and nuts for a permanent Ladder-Aides assembly?

The following bolts and nuts can be used to assemble the Ladder-Aides permanently.

Hex Bolt M6, Medium Strength (Class 8.8), at least 20 mm long.

Hex Nut M6, Medium Strength (Class 8.8).

Flat Washer M6, two per bolt.

They should be available at your local hardware store.