This unusual cable is sort of the 'ultimate' in USB type C Power Delivery (PD) hacking: good for experienced hardware hackers who are comfortable with a cable that can shape-shift from one setting to the other.
Instead of having to juggle multiple wall warts with different power and current capabilities, this cable will convert any USB Type C power adapter with Power Delivery (PD) support into a configurable 5V, 7V, 9V, 10V, 12V, 15V, or 20V DC power port, at up to 2 Amps output.
Inside the cable is a re-programmable PD sink negotiation chip. When plugged into a proper PD Type C adapter that can provide 5/7/9/10/12/15/20V it will chat with the PD source chip in the power supply and tell it "Hey please change your output to, say, 9V thankyouverymuch!" and ta-da, you get 9V out on the DC barrel jack. Do check the side of the adapter you are plugging into to make sure it is a PD source - the voltage and current capabilities will be listed on your adapter.
Note it is not a boost or buck converter - if the power supply only can do 5V or 20V it will not magically convert it to 12V - we do have USB booster cables if that's what you want. So if you program the cable to a 10V DC cable but the power adapter cannot give you 10V out, you will probably just get the default 5V (or no voltage!) out, depending on what the power supply does when the requested power isn't supported.
The voltage output will often be 0.25V to 0.5V higher than the rated voltage so that at high current draw the voltage drop across the cable will still keep it at about the desired voltage at the tip.
The programming software is available in the technical specification section below, it's Windows only - Adafruit ran it on windows 10 with success. It does take a few tries to get the hang of it, but it does work! There are various setting files, load the file and program it into the cable while it's connected with the programmer dongle.
This cable is 1 meter long, so you get just the right amount of length for your project. Also comes with a velcro tie to keep it nicely coiled and neat. Tip is 5.5mm outer diameter, 2.5mm inner diameter but its springy so it works just fine for 2.1mm as well.
Software (.zip file)