A hearing aid for placement on the head of a user comprising: a first part comprising: an acoustic input transducer adapted to convert an ambient sound picked up at an ear of the user to an electric signal, a signal processor adapted to process the electric signal according to specifications of the user into a processed electric signal, and an output transducer adapted to convert the processed electric signal into a transmission signal and transmit the transmission signal inductively, and the output transducer includes a transmission coil configured to inductively transmit said transmission signal, and a second part linkable to said first part by magnetic forces, and where the second part is configured to be implanted into the head of the user, and the second part comprising: a receiver including a receiver coil adapted to receive the transmission signal inductively and convert the transmission signal to an output signal perceivable as sound by the user, and wherein said first part further comprises a receptable adapted to receive an insert element, and where the receptable is arranged in said first part such that said transmission coil surrounds said insert element, said insert element comprising at least one protrusion configured for engaging with a corresponding recess of said first part by rotating the insert element relative to said first part, and said insert element is a magnet module consisting of a magnet holder, characterized in that the connection between the insert element and the first part comprises at least one groove (24a, 24b) extending in an axial direction along a peripheral surface of the insert element or the first part and wherein the first part or the insert element comprises at least one resilient rib arranged on an outer peripheral surface and wherein the at least one resilient rib is configured to engage with the at least one groove (24a, 24b) when the insert element is positioned in the receptacle of the first part, wherein the at least one resilient rib is adapted to be pushed out from the at least one groove (24a, 24b) when rotating the insert element. a first part comprising: an acoustic input transducer adapted to convert an ambient sound picked up at an ear of the user to an electric signal, a signal processor adapted to process the electric signal according to specifications of the user into a processed electric signal, and an output transducer adapted to convert the processed electric signal into a transmission signal and transmit the transmission signal inductively, and the output transducer includes a transmission coil configured to inductively transmit said transmission signal, and an acoustic input transducer adapted to convert an ambient sound picked up at an ear of the user to an electric signal, a signal processor adapted to process the electric signal according to specifications of the user into a processed electric signal, and an output transducer adapted to convert the processed electric signal into a transmission signal and transmit the transmission signal inductively, and the output transducer includes a transmission coil configured to inductively transmit said transmission signal, and a second part linkable to said first part by magnetic forces, and where the second part is configured to be implanted into the head of the user, and the second part comprising: a receiver including a receiver coil adapted to receive the transmission signal inductively and convert the transmission signal to an output signal perceivable as sound by the user, and wherein said first part further comprises a receptable adapted to receive an insert element, and where the receptable is arranged in said first part such that said transmission coil surrounds said insert element, said insert element comprising at least one protrusion configured for engaging with a corresponding recess of said first part by rotating the insert element relative to said first part, and said insert element is a magnet module consisting of a magnet holder, characterized in that the connection between the insert element and the first part comprises at least one groove (24a, 24b) extending in an axial direction along a peripheral surface of the insert element or the first part and wherein the first part or the insert element comprises at least one resilient rib arranged on an outer peripheral surface and wherein the at least one resilient rib is configured to engage with the at least one groove (24a, 24b) when the insert element is positioned in the receptacle of the first part, wherein the at least one resilient rib is adapted to be pushed out from the at least one groove (24a, 24b) when rotating the insert element.