Okay so I've been using this Ruiqas shooting belt for about two weeks now and here's my real thoughts...
The GOOD: This thing actually works! I used to have that annoying thumb interference when shooting, but the strap really forces you to keep your guide hand in proper position. My shot form has improved noticeably.
The BAD: Like some reviews mentioned, if you have smaller hands/thumbs it can be tricky to get the perfect fit. I had to adjust the velcro a few times before finding the sweet spot.
PRO TIP: Don't make it too tight at first - start loose and gradually tighten as you get used to the feeling. Otherwise it might feel uncomfortable during long practice sessions.
Overall? Solid training tool especially for beginners. Just takes some getting used to. Would recommend if you're serious about fixing your shot mechanics!