DDC says:

Great, and not just for climbers I’ve had these for about four years and they are great. The holds are very helpful, even if you mostly use the sloper grips on top. The other holds are good as well, and give a fair variety of challenges. Metolius’ website notes that an open grip will increase your crimp strength (although apparently the opposite is not true, according to them). Because of this, you really can use these as a primary training tool.These are not just for climbers, however. I had stopped using them for a year and switched to regular pull-ups, but when I went back to these, I noticed a big difference. Because they swivel as you work (assuming you haven’t screwed them in), they are gentler on your shoulders and elbows. For me, I noticed a big difference in how the tendons in my elbows felt. Doing regular pull-ups my elbows felt a little strained from the locked in position, but going back to these, my elbows felt a bit better. So, even if you don’t climb, you may want to consider these…