A pair of Kadee magnetic uncoupler magnets. These magnets are fitted between the rails such that the trip pins of the couplers are attracted outwards.
Designed for use with code 100 track, eg Peco Setrack and SL100 Streamline flexitrack.

When the couplers are slackened the knuckles will open allowing the couplers to be parted. Then the Kadee magic comes into play, as the couplers will go into a coupling delay position, a tongue fitted to each each coupler prevents the knuckels from re-engaging and the train can be propelled clear of the magnet. Only when the train is finally separated do the knuckles recentre ready for coupling again.