Jims Black ForceFlow Cylinder Head Fan Kit 5401 Smooth streamlined design will keep your Twin Cam running cooler on those hot summer days in stop and go traffic JIMS R & D department has come up with a serious way to drop the head temperatures by as much as 100deg. Although this mounts in the horn area JIMS has designed a horn relocater hidden inside the fan housing (Kit installs from horn location and is supported by center case bolt location.) The fan can be installed to be turned on and off manually or it can be regulated by a thermostat controlled sensor that monitors head temperature and activates the fan when engine temperature rises This kit is highly recommended for performance motors to help extend engine life