The new tool from X-BOW fma Engineering makes it easy to change the string on the Supersonic crossbow. It consists of two rods which are inserted into the cams during cocking and uncocking, thus blocking them. This keeps the crossbow in a position where the string sits loosely in the cams and has no tension. In this condition, it can be replaced with ease. Included in the delivery are detailed and illustrated instructions explaining two variants for changing the string using the tool. Please note: The tool is only suitable for the X-BOW FMA Supersonic.