We have a scenario where we require our users to enter in a six character hexadecimal serial number from an IOT device into a website textbox. Unfortunately, due to the form factor of the IOT device, the label that has the hexadecimal characters is only about 1'' wide by 3/4'' height. Also, this is a consumer device so our user base has no knowledge of what hexadecimal even is.
In our user studies and in the field we've seen a lot of users struggle with determining what character is on the label. This ultimately ends in us not being able to match up the device's events with the user and the user thinks the system is broken.
Is there a font that is best for the readability of hexadecimal characters, A-F & 0-9, at really small font sizes on a white label? Are there any other suggestions as to how we could make it more readable?