Just got my Diamond Rods in 2 days ago and have had a lot of fun with them.
I had a few knives that were in VERY bad shape and these helped a lot.
They are great when re-profiling a blade. They are very aggressive removers of material.
If you want to cut down the time it takes to bring knives from their current profile to one that is more accommodating for use with the Sharpmaker these are great.
I thought I was too late to get the Ultra Fine stones but a new shipment must have come in recently. I just ordered them and look forward to being able to put a scary sharp edge on all of my blades.
Sure you can re-profile with the gray stones but it can take quite a bit of time. The Diamond Rods are soooooo much faster.
-In Beer there is Strength...
-In Wine there is Wisdom...
-In Water there is BACTERIA...
Old German Proverb