Keeping Missouri Residents Safe Since 1983 CHOOSE AN EXPERIENCED SECURITY SYSTEM COMPANY IN ARNOLD, MO. Trinity Security Inc. is a full-service security system company located in Arnold, MO. Our technicians can install a reliable security system at your residential or commercial property. If you need security cameras, fire alarms or burglar alarms installed, we can make it happen. You can count on us to design a security system that will allow you to monitor every corner of your property, at any time, from anywhere. Call 314-966-2443 now to get your free estimate and arrange for security camera system installation services. If you need an access control system installed, we can handle that, too.