They are both sizes
The two uppers on each side are 3/8" and the lower on each side is 5/16"Are you really sure that you want to put these on? A common opinion is that while they may "look nice" or provide minimal chafe protection, they also trap water and allow salt and corrosion to work on the rigging. I have had them on a previous boat and upon removal found a lot of surface corrosion. I would not recommend them.If you want chafe protection, I use the split plastic shroud rollers. There are wooden ones too but they are more expensive. I have heard of people making their own rollers from 1 1/4" PVC piping (Home Depot) and using end caps that are drilled for the shroud. The down side of this is that you must disconnect the shroud to slip the roller on. You only need one roller per side and it is on the middle shroud. These could be made for under $10-15.Rich