Parker injector razor blades are suited for all vintage and modern injector razors. The blade is inserted in the razor by placing the key of the cartridge (the part that sticks out like finger of a politician shifting the blame) into the side of the razor, the new blade is then pushed into the razor displacing the used blade. This is how it is done...did this razor just get pregnant?!
There are 20 blades in a dispenser and it has space in the bottom of the holder for discarded blades. The verdict is wayyyy out on how many shaves you can get from a blade, I read anything from one to twenty, and like most other blades it also differs by brand. Please help us update our information by providing feedback on the longevity of the blades, as we all know, we shave once a day and the amount of research I can do on my own is very limited.