The Colapz Flexi Waste Pipe Double Adaptor can be used on your caravan, you are able to cut down to size: -
Fits standard double waste pipe outlets fitted on most modern caravans.
Kit includes double adaptor, 15cm downpipe and storage bag.
Very easy to cut the rubberised material to the required size.
6cm adjustment, so will fit most double waste outlets with 7cm to 13cm between centres.   
The rubberised material makes it easy to fit to your caravan waste outlets and provides a watertight seal.
Internal curves to allow free flowing water and prevents any potential backwash to the shower or basins.
Connects very easily to Colapz flexi-waste pipes to provide a watertight seal.
Easy to clean and store in the drawstring bag provided