The MFI Fake Can attaches with 8 allen screws, at the present you have to take the flash hider off to get it to slip over the barrel, but I should have that problem fixed real soon.
As to why would I put something fake on my AR, it has to do with the same reason I have a hand sewn 1780s Brit Regimental coat hanging on my wall, I collect Militaria, and this is as close to having a real M4; Just like I used in the service, as Im going to get.