No.309 under the track electro magnet uncoupler.

A brilliant piece of kit: the #309 through the track (through the ties) electromagnet uncoupler. These are fitted to the baseboards before the track is laid. Track goes over the top so the coupler is completely hidden and does not spoil the ballast and scenery. They prevent unscheduled uncoupling which can happen when permanent magnet uncouplers are used. A push button operates the power when uncoupling is required. A separate power supply is needed to operate these magnet uncouplers.