Doc's Proplugs, the vented earplug for divers: the vent lets pressure equalise while the plug slows cold water washing through the ear canal, which is what leads to surfer's ear and outer ear infections. A solid plug traps an air pocket that can't be equalised on descent, so sealed earplugs and nose clips are kept out of the Scuba range. Earplugs for surface swimming are under snorkelling ear and nose protection.
