Marklin E115737 current conducting couplers for use with Marklin passenger coaches fitted with NEM close coupler pockets. These couplers are the same as in the 72020 sets.

This is one pair of couplers, for one car.

If you have passenger car sets that use the drawbar couplers, and want to couple and uncouple the cars, this is the coupler set that you need. The Rheingold 26750 and 26751 and California Zephyr are examples of sets that can be retrofitted with ease.