At present, he has switched to selling security monitoring products. How can I find a customer?

The simplest and most direct way: HC has a list of engineering suppliers every year, which contains a large number of engineering suppliers and distributors. You can look for it. A thick book, but not a few years ago, because the industry is changing rapidly. Engineers don't know what to do next year this year, so it's better to find the nearest engineering supplier list. Thank you!