I’ve used various versions of those for over 40 years. When they first came out, they were called “crock sticks”. They work great. A total beginner can put a razor edge on a knife the first time. The base material is very important however. Some models with softer plastic or soft wood bases don’t hold up well. The pressure on the sticks eventually starts to make the holes egg-shaped and the angle of the sticks change. Other than that, I love them.