Self-Sealing/ Semi Closed buoys are ideally suited for Liveaboard Divers or divers in remote locations. For Technical divers these are the ideal Deco Buoys for decompression dives.
The other major advantage Self -Sealing Buoys have is that they can be waved above your head to further attract attention. This is particularly useful in remote locations and Liveaboard dive trips.
The expanding air is automatically vented from the Over Pressure Valve during the ascent. If the Dive Marker is not full inflated on the surface air can easily be added by purging your second stage into the opening at the bottom.