Let's talk about this Belt Sander Adapter for Angle Grinder. First off, the idea is genius - transforming your angle grinder into a belt sander in minutes? Sign me up! I've used it for rust removal on old pipes and it's noticeably better than a wire wheel. The sanding action is smoother and more controlled.

However, compatibility is a major issue. Like several reviewers mentioned, it only fits certain grinders. My DeWalt was a no-go, but luckily an old Ryobi in my workshop worked perfectly. The double groove design accepting both 20mm and 40mm belts is brilliant though - makes it super versatile for different jobs.

The biggest headache? Belt alignment. Out of the box, the pulleys weren't perfectly aligned on mine either. I had to add washers (about $0.50 at the hardware store) to get everything tracking straight. Once dialed in, it works great, but that initial setup was frustrating.

Performance-wise, when it works, it WORKS. Sanding pipes became way easier than trying to maneuver a full-size belt sander into tight spaces. Just keep the RPMs moderate - go too fast and the belt will definitely walk off (learned that the hard way).

Final verdict? 3.5/5 stars. It's not perfect and requires some tinkering, but for $30-40, having a compact belt sander option is worth the hassle if you're willing to put in some setup time.