@kennethe62 It’s basically one of these:
https://www.amazon.com/Body-Back-Original-Trigger-Therapy/dp/B00PJ2VN6Y/ref=mp_s_a_1_1_sspa?crid=28HECZFKGDSML&keywords=s+hook+massager&qid=1668710727&sprefix=s+hook+m%2Caps%2C144&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9waG9uZV9zZWFyY2hfYXRm&psc=1
This is...