Choosing type of urethane belt

I would like to know how do you choose the round belt parameters when using it as a conveyor.

For example, how do you choose the belt diameter to fit the pulleys diameter?
Using a solit belt or hollow one?
And what is the preferable hardness?

Just pick 3/16 or 1/4 inch, they both work fine. If you need a tight radius use smaller. I prefer solid.

Watch this for how 1678 welds our belts