Hydra was launched in the pre-OCB era with the legacy binder in all grits

you will not be able to use many good stones

All Chosera stones are 6 mm thick and are mounted on high-quality aluminum blanks

BBW stones are available in 6 mm thickness

bench mount for edge pro apex Hydra was launched in theThe Edge Pro Apex Bench Mount gives you the ability to mount your Apex knife sharpener to any working surface and drastically increases the stability of the machine overall adding great value to your sharpening setup. This mounted knife sharpener is specifically designed for customers who want a more permanent mounting solution or want to sharpen on their wood workbench. The Apex Bench Mount bench knife sharpener is easy to install and can be used