There is another version of this in a straight row available here (
https://shpws.me/M7rl)
This piece is a template for cutting different r-hop patch sizes. It will support up to a 20mm patch, which should be more than enough for even a 12mm ER-hop. It accepts any 6mm ID tubing.
It works much better than the other type of cutter where the template goes around the tubing, especially for soft tubing, which tends not to cut correctly because the tubing collapses.
Using a double sided safety razor is recommended as they are thinner than normal razer blades. Putting a little oil on the blade helps as well.
Sizes are listed in where the cut is relative to the center of the rod/barrel.
Has 6 different sizes you can cut. 2.10mm to 2.60mm. The size is the distance from the center of the rod/barrel where the cut will be made. 2.10mm was tall enough for my 6.23mm orga barrel. The other barrels we have done used the 2.3-2.5mm sizes, but every type of barrel is different. This should include all the sizes you need for almost every barrel.