Installing Tamper Proof Hardware for your signs is not as hard as it may sound. Once you’ve purchased the necessary products, such as the metal and nylon washers, the one-way truss bolt, break away nut (cone-shaped), the post and sign itself, it can be installed by anyone. To begin, look for the widest part of the post to install the sign. Using a screwdriver, puncture a bolt-sized hole into the sign’s vinyl. Then push the truss bolt with nylon washer through the hole so that the washer serves as a barrier between the bolt and the sign itself (this prevents damage). Insert a metal washer on the backside of the bolt and then screw on the break away nut using a slotted screwdriver. As you are doing this, you will reach a point when you can no longer turn the screwdriver. This means you are all done; there’s no need to exert your muscles to try to get it on tighter as with standard hardware. The break away nut as part of the Theft Proof Sign Hardware will then fall off leaving the sign securely in place.
Theft Proof Sign Hardware from StopSignsAndMore: https://www.stopsignsandmore.com/c-165-tamper-proof-hardware.aspx