If you dive the IST Pro Ear Mask, you need the Pro Ear 2000 neoprene Hood. This hood has two layered construction; an inner layer of 3mm neoprene for the placement of the balancing ear cups with an outer thinner layer of 2mm neoprene which adds warmth and a clean appearance. For increased warmth and lowering water exchange while on a dive the hood comes equipped with a smooth skin face and ear seal. Hood is especially designed to complement the protection the IST Pro Ear Mask affords the divers ears. So if your head is getting cold be sure to get this uniquely designed hood.