NeoSport Wetsuits Premium Neoprene 7/5mm Vented Bib Hood neoprene PERFORMANCE: Integrated air vent allows bubbles to escape through the top of the hood without promoting water exchange. MULTI-USE: Designed for warmth while diving at any depth and in any water temperature.MULTI-USE: Designed to keep warm while diving and scuba throughout all weather and water conditions. XSPAN TECHNOLOGY: Exclusive ultra soft material made with 4-way super stretch neoprene.ANATOMIC FIT: Large bib of thinner material provides a comfortable. Tips To Measure: Measuring heads for hood sizes:Neck column: The measurement of the circumference of the neck . Head column: If you measure the head in the same way a headband would fit around it, the number you come up with is what you would look up.