The BbTalkin kitesurf and windsurf advance pack 4-way is a pack for 4 people. Ideal for instructors and users that are all on the water. All headset have waterproof IPX7 rating. This pack is standard equipped with the Surf Hat (B01HR) with speaker and long boom microphone. Your options for the other students depends on your helmet and setup. The mono helmet speaker pad (B02R) is for mono and left side only. The stereo helmet speaker pad (B03R) is for left and right and gives you stereo option for music to. We also have the special GATH helmet speaker pad (B02G) and are only optional if you use GATH helmets only.