For HONDA, HUSQVARNA, STIHL Brushcutters Speed Feed Strimmer Head C6000109
(C6000109, SF400/E1. M10 x 1.00mm Female (most Stihl). 1) Twist the bottom of the head (thread side) to line up arrows with line saver eyelets (silver tunnel shaped). Speed Feed 375 - 400 4" Dia Quick Fill.