We have 3 versions of this design. It is offered in a Large 1", this 1.5" XXL, and a 2.5" XXL.
The measurements given are the thickness of the material you are grabbing on to.
This XXL size offers room for your whole hand to wrap around the handlebar. The 1.5" diameter allows, for most hands, your pointer finger to touch your thumb.
This is a huge hold to help you navigate through really steep sections of wall.