This Demolition Breaker HM1317C Makita Suppression of motor speed during no-load - Reduces vibration of tool body when idling, & decreases the amount of vibration to operator's hands. Minimises deflection of bit tip from aiming point when starting clipping. AVT (Anti-Vibration Technology). Electronic with; - Variable speed control by dial - LED service light that indicates when to replace carbon brush - LED power light that indicates trouble with the electric circuit.