The 2.75 length Power Up Tube carries sound directly to the tip and the ear and can increase amplification by 40%. It's virtually invisible and has enough flexibility to allow for precise position. The occluded Sonic ZTip stays put without the need to readjust and unlike itchy silicone domes which can slip out of the ear canal the Sonic ZTip will always stay in place. The ZTip fits much like an ear mold but does not rely on silicone "tacky properties" for a snug fit so they stay in place all day for up to 4 months providing the most comfortable tip available. This design features natural airflow and directs sound precisely into the ear canal."