For $50, it's worth a shot. Surprisingly hard, especially when resistance is added.
Other versions, namely those with carabiner anchoring points, exist but many would pivot in use when one leg pulled more strongly than the other. And while REP and Force 6 make versions with wider anchoring points, they're also double and triple the price, respectively. And with space at a premium, the extra inches these consume would have limited range of motion.
So, I bought this, threw on some spare soft-loop tie downs and shaft collars, and regret it the next day when the DOMS set in.
Performance
Value
Build Quality