I am looking for a thicker wetsuit beanie to wear with my drysuit whilst cave diving. Most beanies I have found are .5mm- 3mm, with a vast majority being 2 or 3 mm. I'm looking for one in the 4-6mm range (5mm would be perfect). I prefer a beanie because I like to have a wide range of motion of my head. Even though I can wear a hood, if I must, I do not like them,.... too confining feeling. I basically need something to cover my ears. If the water is very much below 70 degrees, I tend to get bad vertigo when the colder water hits my ears The 2mm beanies I typically wear only work marginally well. Anyone have any ideas? Thanks.