Innovative Scuba Concepts Signal Tube Submersible Marker Buoy SMB &ndash; 45 Inch HIGH VISIBILITY DESIGN: SMB is a 45 inch marker that is a high visibility design EASY USE: SMB can be filled by pushing in the inflator valve tube through oral inflation. The air enters the tube through this valve at bottom. RUPTURE RESISTANT: Made from a 420 denier Nylon Fabric with a TPU coating for added strength in all water conditions to ascend without rupturing. Includes safety whistle