This adapter fitting has the M22 Standard male thread at one end (the same that connects to the Rockcar flexible green hose), and has the Karcher quick release hose fitting at the other end.

Solid brass with rubber o ring.  High quality.  High pressure connection.  From Rockcar.  

When in doubt please check your machine and the dimensions on the existing hose/fitting.  

Important: Water blaster manufacturers change hose fittings even between the same models as they change hose suppliers.  Please check your fitting matches the guide before ordering.   Karcher is however pretty consistent. 

This is type 1 on this guide.  Note the flat sides:

Tip:  some Karcher triggers don't allow much space to connect a larger hose, it you are wanting to upgrade to the Rockcar flexible hose, this is the adapter you need to connect to Karcher k series (K2, K3, K4, K5, K7), you may need 2 depending on the connections of your water blaster and current hose.  Some kaarcher triggers have a narrow space between the hose connection and the rtigger, which does nto allow larger hoises to fit, if this is the case with your water blaster trigger you will need to also upgrade the trigger section to this Karcher trigger upgrade which will connect to this quick connect.