For a multimeter the Plugable USB-C Amperage and Voltage Tester (USBC-VAMETER3) manages to fit a lot of useful features into a sturdy little package. About the size of a USB flash drive this bidirectional USB tester allows for full USB data passthrough while it monitors USB-C power and charging measures voltage and amperage even visualizes the directional flow of electrical current-all in real time.
Connect the USBC-VAMETER3 inline between a USB-C host system like a laptop tablet or cell phone and a charger to use it as a USB voltage meter or power consumption meter. An updated OLED screen means a brighter and easier-to-read display in any lighting conditions and a new orientation button lets you flip the screen with a click.

How it works:

This meter is a transparent interposer-it should not interfere with the USB data (1.1 through 3.1 Gen 2) USB-C Alternate Mode video or USB-C charging. The meter can be used in-line with USB-C docking stations chargers and other USB-C accessories. The meter is able to achieve this without interfering with normal USB-C operation as it only taps into the power (VBUS) and ground connections to measure values and leaves the data lines untouched.

Common uses:

Connecting between a USB-C host system like a laptop tablet or cell phone and a charger to monitor charge information.
Connecting between a USB-C host and docking station to monitor charge information.
Connecting between a USB-C host system and a USB-C bus powered accessory like an external hard drive flash drive etc to measure power draw of a device.
Testing for USB-C port spec compliance such as a VBUS hot condition voltage drop under load etc.

Important notes:

This meter is not meant to replace professional USB-C test equipment it is designed for quick/easy measurements for users of any skill level.
Not compatible with Intel Thunderbolt 3 devices.

Specifications:

Meter is bidirectional and can be connected in any direction
Supports 4.5-50V 50mA-6.5A operating range
Support USB-PD R3.1 Extended Power Range (101W-240W)
Supports all USB data (1.1 through 3.1 Gen 2)

More from the Manufacturer

For a multimeter the Plugable USB-C Amperage and Voltage Tester (USBC-VAMETER3) manages to fit a lot of useful features into a sturdy little package. About the size of a USB flash drive this bidirectional USB tester allows for full USB data passthrough while it monitors USB-C power and charging measures voltage and amperage even visualizes the directional flow of electrical current-all in real time.
Connect the USBC-VAMETER3 inline between a USB-C host system like a laptop tablet or cell phone and a charger to use it as a USB voltage meter or power consumption meter. An updated OLED screen means a brighter and easier-to-read display in any lighting conditions and a new orientation button lets you flip the screen with a click.

How it works:

This meter is a transparent interposer-it should not interfere with the USB data (1.1 through 3.1 Gen 2) USB-C Alternate Mode video or USB-C charging. The meter can be used in-line with USB-C docking stations chargers and other USB-C accessories. The meter is able to achieve this without interfering with normal USB-C operation as it only taps into the power (VBUS) and ground connections to measure values and leaves the data lines untouched.

Common uses:

Connecting between a USB-C host system like a laptop tablet or cell phone and a charger to monitor charge information.
Connecting between a USB-C host and docking station to monitor charge information.
Connecting between a USB-C host system and a USB-C bus powered accessory like an external hard drive flash drive etc to measure power draw of a device.
Testing for USB-C port spec compliance such as a VBUS hot condition voltage drop under load etc.

Important notes:

This meter is not meant to replace professional USB-C test equipment it is designed for quick/easy measurements for users of any skill level.
Not compatible with Intel Thunderbolt 3 devices.

Specifications:

Meter is bidirectional and can be connected in any direction
Supports 4.5-50V 50mA-6.5A operating range
Support USB-PD R3.1 Extended Power Range (101W-240W)
Supports all USB data (1.1 through 3.1 Gen 2)

More from the Manufacturer