Don't be confused! This is just a 1/8" version of the traditional TRS-to-XLR cable. It is wired Tip-3/Ring-2/Sleeve-1.
If you use this cable to connect the headphone jack of a phone or laptop to the XLR input of a professional sound system, you will get *strange* results. Playing music, you will hear many instruments, but most vocals will be faint. Playing speech, like a podcast, the voices will be *barely* audible!
This happens because of the electrical difference between the "unbalanced" 2-channel stereo source (left/right/ground) and the "balanced" 1-channel XLR input (+ input/- input/ground).
To properly connect that phone or laptop, pin 3 of the XLR must connect to both the tip and ring through _separate_ 1000-ohm resistors. Pin 2 connects to the sleeve. (Pin 1 may also connect to the sleeve.) This will give you monaural (1-channel) sound, but you *will* get *all* of the sound!