The ceramic swival knife blade, there are 4 sizes:
7mm oblique blade
7mm single blade
10mm single blade
10mm double blade
Please choose what you need, the diameter of the pole is 5.2mm, you can see it can fit almost all kinds of swival knife.
The ceramic swival knife blade is better than steel one, it no need sharp, just need to polish it a little on polish board before use.
You can buy the polish board here: