Flat Belt Pulley. Here we have a genuine original cast iron pulley,  it fits a 1  1/2 inch shaft,  it's a 5 inch pulley  and is 4 1/2 inches wide where the belt runs. However  it does have a very small crack   just at the start of where the Woodruff Key fits, someone has hit the Key in to hard.  But it's only a chip and if fitted towards the Flywheel it won't be noticeable.  The rest of the pulley is fine.