VEVOR Scaffold Outrigger Outrigger Set 18" x 18" 4 Pcs w/ Locking Pin and Wheels

I know it says 4 PCS, but is that four OUTRIGGERS including CASTERS? or are there 4 PCS to each outrigger?

I want to buy these for safety. For my existing scaffolding. But, I have a smaller type scaffolding. My scaffolding has square tubing 1.5" .. so these dimensions don't show measurement size to slip over pipe. It shows length, but that to me is irrelevant. Will it slide over 1& a half inch tube? If it does, I will buy them. Thank you for your time. John.

What size wheels are on the casters? 4" or 5"?

Dose this fit a werner 6 ft. Scaffolding