Crowdguard provides temporary event security solutions by installing security barrier systems. They also offer installation services for the Surface Guard system which is designed to provide hostile vehicle mitigation and temporary event security for stadiums, festivals, urban squares and VIP visits.

Crown Security Services based in Brimingham offers a range of services, such as manned guarding, CCTV remote monitoring, keyholding & alarm response, mobile security patrols & construction site security. Crown Security Services provide an off-site CCTV monitoring and protection service for commercial, industrial and residential premises through the use of remote digital technology, cameras and motion activated CCTV systems.

CTG Security Matrix is an organisation devoted to providing operational advice and recommendations to guide the planning, design, documentation, installation, maintenance and future upgrades of electronic surveillance systems and control infrastructure.

Cybersecurity and Infrastructure Security Agency leads the national effort to protect and enhance the resilience of the nation's physical and cyber infrastructure. CISA's multi-faceted mission is home to more than 15 career fields, including business administration, cybersecurity, programme management, communications, data science.

Cyelcor Ltd offers solutions such as CCTV, Intruder Alarms, Security Smoke Systems, Fire Alarms, Access Control, Video Door Entry Systems, Smart Home Automation, Oil & Gas Telemetry, Systems, Automated Swimming Pool Dosing. The company also provides consultancy services for home and business owners.

Cyral is the first cloud-native security solution built for the modern data cloud and the DevOps-first world. With Cyral, DevOps and security teams get granular visibility, secure access management and policy enforcement across all data endpoints for an unmatched unified view of any organization’s data layer activity. Cyral is venture-backed by Redpoint, A.Capital, Costanoa and SVCI.

D-Ron Group is a leading technology solutions provider that delivers end-to-end solutions to transform its customers' ICT infrastructures. Headquartered in Singapore, the company provides a holistic suite of ICT, Surveillance Products and Services. The company is now the region’s trusted brand for the Security and Surveillance sectors. Their regional network span across Malaysia, Taiwan, Thailand, and China.

D.W. Price Security was established in 1998 by the current directors who each have more than 30 years experience within the physical security sector. They are the 3rd generation of the original family business, with roots based in the original glass and glazing industry with the first security installations carried out in the early 1970s.

D&D Security Derby offers fully licensed SIA-approved security guards that are ready to be deployed within hours upon acceptence. It provides approved contractor security services for major companies across the UK. Specialists in static guarding, it offers a cost-effective security service for the protection of UK businesses.

DA Security Systems are a family run CCTV, Fire and Alarm Business. It has been operatiing from Lee-on-the-Solent in Hampshire, UK since 1984. It has over 40yrs experience with the installation and maintenance of CCTV, Fire Alarm, Intruder Alarm, Door Entry and Nurse Call systems.

Daifuku Airport Technologies is a solutions provider for airports worldwide. They specialise in airport operations and maintenance, baggage handling, self service technology, automated bag drop, baggage tray systems, tilt tray sorter, mobile inspection Table, early bag storage, hold bag screening, RFID and other solutions.

Dakak integrated systems is one of the most prominent security solutions firms in Egypt, delivering up to date products, providing cunning consultations, tailoring solutions to fit situation at hand for leading corporations and institutions throughout Africa and the Middle East. The company serves has a strong presence in aviation services, public safety, data centres, energy infrastructure and government facilities, among others.

Danaide SA is a company dedicated to providing turnkey electronic security technology solutions. The Argentina based company offers video surveillance, commercial vehicles with embedded video, capture license plates, access control, fire and alarm detection and intrusion detection to private or government sector.

DAS Technology can design, install and maintain security systems for a wide range of uses from homes, shops and offices to shopping centres, schools and car parks. They provide bespoke security solution that meets your needs, and all completely hassle free. Their nationwide network of engineers is trained to the highest standard in order to install security systems with a professional, efficient and reliable service.

Data Installers Inc. is an IT infrastructure design and network cabling Installation Company. The company specialises in the sales, service, and installation of structured voice and data cabling systems, voice and data integration, fiber work area products plus fibre optic cabling systems. Its complete CCTV surveillance system solutions provide enables users to monitor and view their office or home with computer or smartphone.

Datapoint Microsystems Ltd is a leading supplier of ICT and Security systems training courses. The company provides professional certificate courses to installers, operators, managers and designers of Closed Circuit Television (CCTV), Network IP, Intruder alarm, Access control, Fire and Burglary alarm systems and all other types of electronic security systems.

Datacomm Express is a leading provider of end to end security technology equipment in Nigeria. The company consults, supplies and installs video surveillance equipments, fire safety and protection equipment, home automation and alarm systems, access control solution including biometric, password control devices.

David-Link targets the wholesale and OEM/ODM market supported by quality products with competitive prices direct from the manufacturer. Along with the advantages in prices and quality, David-Link also offers customisation of products and software that best meets individual business’ needs.

DCI was started by a group of young entrepreneurs with an objective of providing electronic security systems / products at best price and support. At present, they are engaged in the field of security surveillance systems, security control systems, access and attendance recording systems, fire safety alarm systems, CCTV and home appliances & healthcare products.

DC Solutions is a CCTV installer based in Luton.

De La Rue works with governments, central banks and commercial organisations around the globe in producing banknotes, product authentication fighting illicit trade and counterfeiting and in the supply of key security components to the identity industry.

Defero Technology is an innovation-technology enterprise which has been focussing on providing customers with commercial automation and intelligent parking management systems. Defero has independently developed the AD01 series of embedded control system, multi-link communications bus control technology, and obtained 20 more patents.

Definitive Electrical supplies, installs and services many types of security system; from small residential to large commercial and warehousing systems. Ness & Hills have systems to suit any installation and budget. All alarm systems have easy-to-use touch screen keypads, battery backed up operation and back to base monitoring abilities. Other options include radio detectors, door sensors and glass break sensors.

Delaney Hardware is a renowned provider of premium builder hardware for residential homes, multi-family buildings, and commercial projects. As part of the Sargent and Greenleaf (S&G) family of brands, Delaney offers a full portfolio of hardware including door hardware, digital locks, barn door hardware, bath accessories, commercial hardware, trim hardware, steel doors and frames.

Delaney Secure Ltd is an IT security distributor specialising in biometric authentication, door entry systems and PCI DSS compliance. Leading stockist of door entry solutions, time and attendance, fingerprint readers, palm vein readers, iris scanners, face recognition and OEM biometric hardware and software solutions.