A guard assembly for an abrasive accessory of a power tool, comprising: an inner guard secured to the power tool around an output spindle of the power tool; and an outer guard secured to the inner guard at a pivot point along or in close proximity to an axis of the spindle, the outer guard being rotatably movable with respect to the inner guard around the pivot point between a retracted position, wherein the inner and outer guards together cover a first angular area of the abrasive accessory, and an extended position, wherein the inner and outer guards together cover a second angular area of the abrasive accessory larger than the first angular area, the guard assembly including a lock assembly disposed on an outer periphery of the outer guard, which lock assembly is configured to secure an angular position of the outer guard assembly with respect to the inner guard; wherein the lock assembly comprises a spring-biased actuation member actuable by a user against spring force and an engagement portion extending from the actuation member around a pivot member secured to the outer guard, and wherein the inner guard comprises a plurality of peripheral slots engageable by the engagement member under action of the spring force; the guard assembly characterised in that the inner guard comprises a guard shell associated with a first surface of the abrasive accessory and secured to the power tool around the output spindle of the power tool; and a guard cover being associated with a second surface of the abrasive accessory opposite the first surface and attached to the guard shell at a pivot point having an axis that is at a distance from the axis of the spindle, the guard cover being rotatably movable with respect to the guard shell around the pivot point. an inner guard secured to the power tool around an output spindle of the power tool; and an outer guard secured to the inner guard at a pivot point along or in close proximity to an axis of the spindle, the outer guard being rotatably movable with respect to the inner guard around the pivot point between a retracted position, wherein the inner and outer guards together cover a first angular area of the abrasive accessory, and an extended position, wherein the inner and outer guards together cover a second angular area of the abrasive accessory larger than the first angular area, the guard assembly including a lock assembly disposed on an outer periphery of the outer guard, which lock assembly is configured to secure an angular position of the outer guard assembly with respect to the inner guard; wherein the lock assembly comprises a spring-biased actuation member actuable by a user against spring force and an engagement portion extending from the actuation member around a pivot member secured to the outer guard, and wherein the inner guard comprises a plurality of peripheral slots engageable by the engagement member under action of the spring force; the guard assembly characterised in that the inner guard comprises a guard shell associated with a first surface of the abrasive accessory and secured to the power tool around the output spindle of the power tool; and a guard cover being associated with a second surface of the abrasive accessory opposite the first surface and attached to the guard shell at a pivot point having an axis that is at a distance from the axis of the spindle, the guard cover being rotatably movable with respect to the guard shell around the pivot point.