So disclaimer I'm a DIY electrician not certified or anything but I really like these junction boxes for old work. They are far superior to cheap blue boxes with plastic tabs that break or cannot support much weight due to drywall strength limitations. This is great because you're drilling them into the wooden studs in your wall. Of course, this can become an obstacle if you're trying to install in the middle of a rack rather than to the side of the rack. But I always cut holes in old drywall for studs and then screw these bad guys right into the stud. As such, they are as durable as any new building junction box. They won't wobble, move, or move when properly installed. The screws are included and did not break when installing with an impact wrench. However, due to the angle they are at, it is a bit difficult to line the box up precisely with the drywall, but be patient and you will be rewarded with a solid, durable box. They are more expensive than the standard J-Boxes so I gave them 4/5 stars for value for money but it might be worth the cost as they will last longer than I likely will.