Four back is a blanket term for a variety of PP breakouts that don’t involve a drop pass. #4 pushes up and then moves across the offensive blue line to manipulate the back half of the PK structure. The remaining skaters swing back to build speed and manufacture passing options. In the example above, #3 and #5 form a Double Left Swing. #2 stays right and skates into the space vacated by #4.
Certain European teams use a Five Back for additional low support, but the absence of a dedicated push player allows the PK to step up as a unit and deny the red line.