The latest version of the PF-22 MTM foam cannon now comes with the 1.1mm orifice, but the older ones and the current Original one does not. This is needed for your lower-end electric pressure washers like SunJoe, AR Blue, Ryobi, etc.
The idea here is to decrease the size of the hole, creating more pressure, and allowing you to get better foam on your lower volume machine.
You would not want this for and gas or higher powered electric pump like a Kranzle. It could cause damage.