Getnet GN-621U

Wireless 300Mbps USB Adapter

Drivers available on getnet's page are for RTL81xxSU ( RTL8712U ).
 * USB ID mention (0bda:8172 - default RTL8191SU USB ID) on Ubuntu Forums

Dimensions, per getnet, are Dimensions::9 mm x 19.2 mm x 56 mm.