A carrier for a two-component developer, includes: magnetic particles and a resin coating layer that is coated on the magnetic particles, the resin coating layer containing metal nitride particles having a volume average primary particle diameter of from about 300 to about 2,000 nm. When retracted, the coil’s sections are collapsed around each other, held together in the retracted position by a sheath that, when distally retracted, allows the coil to automatically expand. The throttle is formed by at least one transfer area having a predetermined cross-section in a valve element which interrupts the fluid flow up to the transfer area at one of the valve positions and releases it at its other position.