I got a pair from the above site because I was in a hurry and ordered limiters from Felder. I was able to use these with limiters from the rebate set for the job. I have Felder safety cutterhead which is 100 mm dia. I am told that Felder 50 mm head can use 40 mm knives.

Bottom line, I wanted to try them and did a project. Obviously, this produces a joint that will withstand substantially higher shear forces but I have so far not have an application requiring it. I guess it can ease assembly.

Just sharing my experience. Hope you find it helpful.