Review on Handiwear: 2 Pack Water Bottle Carrier Grip for Running - Convenient Soft Band Holder Strap for Handheld Use. Perfect for Biking, Gymming or Jogging! by Brian Vasquez

So far it's doing exactly what I wanted. I have arthritis in my left thumb and the water/all-purpose thermos is too big to comfortably lift. I searched Revain for "water bottle handle" and they came up. I have 2 packs which is great because I have a lot of water bottles/thermos. (it's an obsession) I wet the thermos first, which helped him move around more easily. It fits well, but that's what you need to keep it in place. I have it on a thermos, like the picture, with a loop that I put my two middle fingers through and put the thermos in my palm when I pick it up. Voila - no pressure on the thumb. Love it - buy it - you won't regret it! PS the thermos is an open ended 24oz for $10 which is great too. I had no problems with it and dropped it on the pavement, it cracked part of the lid but it still closes and snaps shut and keeps the drink in without spilling. (I have two) I would say this thermos is at least 3 inches in diameter, maybe more.