Serving DE, MD, NJ & PA

Security Instrument is Delaware’s largest full-service independently-owned security company, serving thousands of customers throughout Delaware, MD, NJ & PA.

Commercial Case Studies

From Fortune 500 to local SMB’s throughout the Tri-State area, Security Instrument integrates custom security systems to meet the needs of our commercial clients.

Customer Service

SI takes great pride in over 60 years of excellent service. When you need us, we are there, with 24 / 7 alarm monitoring and centralized local service for homes and businesses.

What Our Clients Say

Service in over 47 counties in Delaware, Maryland, New Jersey & Pennsylvania!

“Our Team here at Bayshore has utilized Security Instrument for securing our warehouses, temperature and humidity controlled Fine Art Storage and many other storage services for over 25 years!  SI (as we call them) has proven to be a true partner and then some!  SI has continually invested in the needed technology and the PEOPLE – the TEAM at SI is responsive and on top of things – when you get the call at 2 am about a motion sensor going off and you’re 2/3 asleep it is nice to have a professional person on the other line with accurate data.”

One Instrument, Total Security.

With over 60 years of experience in the commercial security and life safety environment, we offer a wide selection of products from some of the most trusted manufacturers in the industry. Our clients can choose from a full complement of personalized support services to back-up their system and help safeguard their people and property.

Customer Service Is Priority #1 With SI.

Security Instrument maintains a dedicated customer service team focused on delivering the most reliable, friendly, professional service and support available.

Combined with our state-of-the-art, local UL listed  central monitoring center, your can rest assured that we are always available when you need us.

A Few Of Our Technology Partners

SI integrates hundreds of products from our strategic partners.
The list displayed here is a sample offering.


Delaware Offices To Serve You

30 +

Vehicles On The Road Daily


Monitoring from Delaware’s only UL and FM listed central station.

Security Instrument Ranks on the SDM 100 Report

We’re pleased to announce that Security Instrument made the SDM 100 list for 2020, illustrating the decades of experience we bring to our customers. Founded in 1960, Security Instrument offers a full line of professional security services and products serving thousands of customers in Pennsylvania, Delaware, Maryland, and New Jersey. Here is more on the SDM 100 list and why it sets us apart.