This course is for advanced cave explorers. When you are far away from the entrance and your scooter is broken you are in big trouble. The way back by fins can give you such a big deco time that you are not able to survive. So, you must have a backup dpv. You can carry it in a classical way - on the rear end or in a modern way - jointed DPVs in front of you. What is the benefit of using the new way? When your backup DPV is on the back of you, you are not able to control it and you can badly catch something with the scooter or stuck in the restriction. When the backup DPV is in front of you, you control everything and avoid the risk of the scooter on the rare end. Before the restriction, you can easily split two scooters just with one click and push them one by one in the hole. After the restriction with the same one click you connect two scooters in one dual dpv and go. If one of the scooters is broken, you can just go back using the workable DPV or disconnect the broken one and leave it in the cave. Furthermore, the big benefit of dual diver vehicle propulsion (DPV) in front of two separated scooters is the bigger speed and the torch moment. So, you move faster, you see two scooters in front of you and control them perfectly, you can connect and disconnect the dual dpv in a second. My opinion is Seacraft scooters nowadays are the best on the market for a lot of reasons and the scooters and the platform that allows to connect two DPVs is done well as well. You can come to me and try the scooters for free of charge.