Original OEM (Original Equipment Manufacturer) mega fuse 500Amp / length 55mm, Part No. 1273. The fuse is located on all new model 12/24V European Boosters and is located on the Red Clamp. To access and replace fuse pull the red palm grip sleeve along the black cable and unscrew the two 10mm nuts that hold it in place. 

This fuse is located on the Red Clamp as shown in photo