I was introduced to this liniment in 2010 by one of my first bodywork teachers. Zheng Gu Shui ("jeng goo schway") is basically translated as "Heal Bone Water" and this stuff is like liquid Tiger Balm on gear.
Great for muscle pain, back pain, post-workout soreness, pre-workout prep, bruises, especially if acute.
It smells great - well, I like it anyway - and can stain, so use it with old clothing, or clothing you don't care too much about.
Get the bottle with the applicator - it's easiest to apply. Topical use only.
Disclosure: Don't be daft. Use it as it was meant to be used. Don't use it on mucus membranes, open wounds, sensitive areas, etc.