An injector device is disclosed, the injector device comprising an elongated mixing container extending along a first axis, and a piston member slidably positioned in the mixing container. The injector device comprises a mixing device comprising a mixing member, an elongated member parallel to the first axis and a handle member. The piston member comprises a piston head and a first locking arm flexibly connected to the piston head, such that the first locking arm in a first position extends substantially parallel to the elongated member and engages with the mixing device in such a way that the piston member moves in a first direction along the first axis with the mixing device. In a second position, the first locking arm may allow the mixing device to move relative to the mixing container independently of the piston member.
