The invention relates to a valve (1), comprising a body (2), within which a needle (3) moves, which can rest with sealing against a seat (23), fixed to the body (2). The needle (3) is magnetically coupled to an actuator body (5), across a closed and a magnetic chamber (4) provided with several magnets (52) between which magnetic bodies (53) are interspersed. The needle (3) has no magnets and is provided with ribs (36) made from a magnetic material. According to the invention, an improved magnetic coupling may be achieved, whereby the thickness and the relative separation of the ribs (36) are largely equal to the thickness (e53) and the relative separation (l52) of the magnetic bodies (53).