This Spare Blade Set is intended for the Double Wide Mars Coat King, 12 blade. This blade is intended to be used with coarse hair or fur. Naturally you can also use these spare blades in addition to your normal width Curry-Comb. The installation is very simple. Loosen the two cap nuts of the old head, you don’t need to unscrew these too much (7mm open-ended spanner), click in the new head and it is important to mind the mounting angle to the holder. This should set in slightly tilted.(best you mark the installation position of the old head) Now the cap nuts always tighten up in turns and thereby secure the head with which it can not twist.