I only know the details that are on the link I posted.
They are 6ft long.
I don't know the diameter.
"This handle is a 1 piece handle , 6ft long with an Abbreviated Duplon Handle. Carcon Composite Handle that is very light , yet extremley strong. With a Brass end fitting this handle is a quality piece of kit.
As part of the deal we will send this handle to you in a very strong and sturdy 6FT Rod Tube to keep it safe in transit and also in your holdall.
This handle should sell at £19.99 and the rod tube at £4.99."