A power tool accessory mountable to a power tool, the power tool accessory comprising: an accessory output; and a second induction coil configured to receive electrical power wirelessly transmitted from a first induction coil of a power tool in use to power said accessory output; characterised in that the tool accessory is a dust extractor for a hammer drill which comprises: 1) an inlet comprising an aperture through which a bit of a hammer drill can be arranged to project; 2) an electric motor and a fan wherein the accessory output comprises the electric motor driving the fan to draw dust laden air into the inlet; and 3) a filter to filter dust from the air drawn in through the inlet; wherein the second induction coil is disposed in the dust extractor at a location in which, when the dust extractor is connected to a hammer drill, current through a first induction coil induces a voltage in the second induction coil through inductive coupling to drive the electric motor of the dust extractor by inductive power transfer from a source of electrical power for the hammer drill. an accessory output; and a second induction coil configured to receive electrical power wirelessly transmitted from a first induction coil of a power tool in use to power said accessory output; characterised in that the tool accessory is a dust extractor for a hammer drill which comprises: 1) an inlet comprising an aperture through which a bit of a hammer drill can be arranged to project; 2) an electric motor and a fan wherein the accessory output comprises the electric motor driving the fan to draw dust laden air into the inlet; and 3) a filter to filter dust from the air drawn in through the inlet; wherein the second induction coil is disposed in the dust extractor at a location in which, when the dust extractor is connected to a hammer drill, current through a first induction coil induces a voltage in the second induction coil through inductive coupling to drive the electric motor of the dust extractor by inductive power transfer from a source of electrical power for the hammer drill. characterised in that the tool accessory is a dust extractor for a hammer drill which comprises: 1) an inlet comprising an aperture through which a bit of a hammer drill can be arranged to project; 2) an electric motor and a fan wherein the accessory output comprises the electric motor driving the fan to draw dust laden air into the inlet; and 3) a filter to filter dust from the air drawn in through the inlet; 1) an inlet comprising an aperture through which a bit of a hammer drill can be arranged to project; 2) an electric motor and a fan wherein the accessory output comprises the electric motor driving the fan to draw dust laden air into the inlet; and 3) a filter to filter dust from the air drawn in through the inlet; wherein the second induction coil is disposed in the dust extractor at a location in which, when the dust extractor is connected to a hammer drill, current through a first induction coil induces a voltage in the second induction coil through inductive coupling to drive the electric motor of the dust extractor by inductive power transfer from a source of electrical power for the hammer drill.