Two buttons and two for interaction To run zigbee2mqtt for the control of Zigbee products like BASICZBR3, S31 Lite Zb in your home automation system, a CC2531 USB dongle integration is recommended. The CC2531 USB dongle is a fully operational USB device which provides a PC interface to IEEE802.15.4 / ZigBee applications, comes with a CC2531ZNP-Prod firmware, the dongle can be plugged directly into your PC/Raspberry etc used as a Zigbee packet sniffer. Yup, it is a -to-go CC2531 USB dongle for zigbee2mqtt application Flashed with CC2531ZNP-Prod firmware for zigbee2mqtt application Lead out 8 IO Debug interface Size: 5.6 x 1.6x 0.7cm State of Assembly: -to-Go Compatibility: All Compatible Model Number: Zigbee CC2531 USB Dongle color:As shown Material:PC+Metal Package Contents: 1 x USB Dongle Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.