Added some security to Wet Sounds Pro 485s

I'm in the process of installing a pair of Wet Sounds Pro 485s. The collars that attach to the tower and speakers use M8 stainless socket head cap screws. I wanted to replace these with a security head screw. I was not able to find and off the shelf/internet screw that was stainless, metric and had a security head in a socket cap. I had the machine shop that I use add a center pin to the readily available stainless socket cap screws. I know that if somebody wants the speakers they will eventually get them, but at least it may take them a couple tries. Here's a picture of what the security bolts look like: