STIHL FSA90 R | Battery Trimmer Autocut 25-2 STIHL ECOSPEED ADJUSTMENT OF ENGINE PERFORMANCE. With the help of STIHL ECOSPEED, you can regulate the engine speed as required and adapt your power tool’s performance to the job at hand. Where applicable, this results in lower fuel consumption and quieter operation. Additionally, this function can reduce the tendency for cuttings and stones to be flung out during mowing. CARRYING RING FOR SAFE STORAGE. The power tool has an integrated carrying ring. This allows you to store your power tool safely and compactly. SAFETY LOCKING LEVER PREVENTS INADVERTENT START-UP. The safety locking lever prevents your power tool from accidentally starting up when the battery is inserted. If you want to secure your power tool, move the lever to the provided safety position on your power tool. If you want to resume work, you must unlock the power tool again using the lever.