I bought these few weeks ago for my Sony projector, but after mounting and using for 2 days, I returned the projector and bought a BenQ. The BenQ is a much bigger projector and I wanted to keep it flush to the ceiling grid, so had to buy a different mount. All hardware if included.
Chief sells their mounts a la carte and this mount does not come with a downrod and ceiling plate. If you already have a ceiling plate and a 1.5" diameter downrod (even if it's another brand), then you don't need to replace them. Just make sure your downrod ia 1.5" diameter and has male NPT thread, so that this mount can be attached.
If you want to buy the downrod and ceiling plate, then here are the links -