Instruct: Classify Amazon reviews into positive or negative sentiment
Query: don't know how it works but man does it work

my dad who has arthritis, chronic back pain, and frequent knots in his neck from golf - and he just swore by this spray - always saying how great it feels.well we bought a bottle and he was SO correct.purchased this case as my dad is just regularly using it for this aches and muscle pains - and it actually works! (and pain medicine, chiropractors, accupuncture, and surgery all failed to relieve his pain)