The product is specifically a strap‑lock style accessory aimed at acoustic guitars with end‑pin output jacks. 
The “PW‑AJL‑02” model is for guitars with the Taylor Expression System built‑in jack (i.e., the end pin jack in many Taylor acoustic guitars). 
It works by having a loop through the strap’s end and then a cinch/clamp mechanism which locks around the end‑pin jack, meaning the strap is securely held without needing the user to modify the strap.