Mono cables are used for most all acoustic-electric guitars and single pickup electric guitars which are a two conductor, tip and sleeve (TS). Since single pickup guitars have only one pickup, they only need one signal line and a ground, and since most all acoustic-electric guitars have only one microphone inside the body of the guitar, they too usually only require a mono cable.
TS 1/4’’ (6.35mm) Mono Cable
Stereo cables are used for “stereo” output guitar jacks. Stereo jacks are commonly found in dual pickup electric guitars which are a three conductor, tip, ring, and sleeve (TRS). There will be a signal line for each pickup and share a common ground. Keyboards, mixer boards, and electronic drumsets although usually stereo can sometimes be mono, the owners manual would have to be checked.
TRS 1/4’’ (6.35mm) Stereo Cable
Plugging a mono plug into a stereo jack will make the output mono, and in some cases may cause damage to the device (typically in active or amplified stereo jacks). Plugging a stereo plug into a mono jack will most likely play tone out of the right speaker but not the left unless you are going from a mono jack to another mono jack, then a stereo cable will work fine and will play as mono.
Below is a list of IO Audio Technologies high quality (mono and stereo) 1/4’’ phono audio cables:
Features: shielded, high tensile strength, high flexibility/durability, oxygen free copper (OFC), twisted wire for crosstalk reduction, easy on hands when coiling for storage.