TOP4503P is a fully molded 4U rack-mounted industrial control chassis. The outer surface of the chassis is completely sandblasted black. The chassis can be installed with standard ATX/Micro-ATX motherboards and supports four 3.5-inch hard drives and one 2.5-inch SSD. Supports standard ATX power supply, compatible with 7 PCI/PCIE expansion slots, supports 2 5.25-inch large optical drives, comes standard with 1 12 cm fan, and the rear window is designed with 9 DB9 and 2 DB37 knock-out interfaces for easy expansion. It is widely used in industrial control, intelligent transportation, mechanical automation, Internet of Things, security monitoring and other fields.