Simply put.
USB based Z-Wave antenna used to build a gateway with open-source software.

This is the 2020 upgraded model from Aeotec featuring compatibility with Raspberry Pi 4, Smart Start and Security 2 (S2) encryption. 

Details.

• Works with Raspberry Pi, Windows, Mac, Linux to create a z wave hub for control of Z-Wave and Z-Wave Plus devices.
• Easier device setup than standard Z-Stick Gen5. Now supports SmartStart device installation when used with compatible software connect Z-Wave devices simply by scanning compatible QR codes
• More secure than standard Z-Stick Gen5. Upgraded to offer Z-Wave Security 2 (S2) encryption, this Plus edition of Z-Stick is enhanced with AES 128-bit encryption, ECDH key exchange, and pro-security grade UL 1023 compliance
• Faster than standard Z-Stick Gen5. Plus edition offers a 50% speed performance when communicating securely vs. non Plus edition. And can be used to upgrade the firmware of compatible Z-Wave Plus devices that can accept OTA / wireless firmware upgrade.

More information

Aeotec maintains Z-Stick Gen5+ user guide and setup information at that link.

Gateway compatibility please check aeotec.com/z-wave-gateways here.