This is the Keweisi KWS-V20 USB tester.
Can easily measure the USB ( PC USB, cell phone charger, car charger , mobile power , etc. ) port and device operating current and the output voltage charge-discharge capacity, performance, and judge the performance of the charging cable charging equipment, this tester can meet the requirements !
No additional power supply required, it is plug and play.
More information can be found here.