There are currently four types of holds in the climbing industry. We make them out of the same polyurethane resin. However, the difference between is how they attach to your wall. Below are types with the pros and cons of each.
Bolt-on holds attached with a single 3/8-16 Allen Head Socket Cap Bolt. The Allen Head Bolt has been the industry standard for decades. The pro is that they can be easily moved around for route setting. The con is that they can spin.
The addition of the spinner screw solves the spinning issue. Now the hold attaches with a 3/8-16 Allen Head Socket Cap Bolt plus a screw. The screw is usually a wood screw, a deck screw, or a concrete screw. Climbing gyms love them to keep their holds in the exact orientation they want them to be. Outdoor walls and playground love these because even with the expansion and contraction of the wall, the grips stay put. The con is that you do have to install the screw and take out the screw each adjustment.
On that note, many think that they do not want screw holes all over the wall. Using screws on a wall is standard practice and should be embraced rather than avoided.
The Screw-on hold attaches with two to five screws per hold. The ropes course industry has migrated to these because no matter how thick the wall gets, a Screw-on screws into anywhere there is 3/4" of wood or thicker.
The pro here is that the hardware compared to Bolt-on is less expensive and that the hold will never spin. The con is that you have to remove up to 5 screws to move the grip. Screw-on holds are best suited for walls that will have the holds in more permanent locations.
2-Bolt Playground climbing holds take playground walls to the next level. With two 3/-16 Allen Head Socket Cap Bolts holding them in place, they will never spin. The con with these is that some sets have tooling ( the space between the bolts) that is not the same as the other holds. This is why we designed the 10 Pack 2 Bolt. It has the exact same spacing and depth in relation to the bolts. It is the very best set in our 2 Bolt line.
The pro here is that you have a hold that will never spin or pull out. The con is that you are using double the amount of hardware when compared to a Bolt-on.