The pictures and the detail description text do state that the gun is priced without muzzle device and that you can add a muzzle device if you choose to do so (at additional cost)... there's a drop down menu listing various options to choose from.
Muzzle devices shown on the item page include everything from an A2 to a PWS FSC556 to several fake cans... each is shown and priced accordingly.
The barrel has a thread but only one thing can be threaded on so if you choose to put a fake can then you can't screw on anything else without first removing the can.
Mark