Feature: 1. Simple operation, most serial commands are single‑byte commands. 2. With capacitor filter circuit, which has improved stability. 3. Onboard 2 relay, which can be accessed extended 2‑way relay module. 4. Two‑channel relay, plus two expansion IO ports, low‑level output. 5. Built to meet standard specification, strictly follow factory quality control. Specification: Condition: 100% Brand New Item Type: Relay Switch Board Material: Plastic Color: As picture shown Two-Channel Serial Relay: Channel: Two-channel relay, plus two expansion IO ports, low-level output Interface: DB9 female/male RS232 level, can control the relay on, off, self-locking, inching through the super terminal (serial port debugging software) on the computer. Working Voltage: DC 12V power supply (range: 8.5-13.5V) Control Voltage: DC 9V 12V or DC 1-48V or AC 85-265V Control Current: 10A . Package List: 1 x Relay Switch Board