Shell is made of aluminum with a rubber/TPU pad on the bottom to keep it in place on a flat surface. I typically wear just one earbud (I like to be able to hear things going on around me in the real world), and with the Tribits, I can take either one out of its case and use it by itself with no extra steps required. No wondering what size to be, these are true to size! I dont need to take my gloves off to answer calls. kurze Kabel für unterwegs und lange Kabel für zuhause), aber nicht zwingend. So if you are a half size (ie. They recently updated the product image but the assembly instructions are out dated. Unfortunately, the cushion didn’t last. They are so comfy and cute. If you want a nice comfortable gift for a guy, then get this!