SX101 
SX060 
ST100 
ST055
There are several different server units. All ST models are made out of prims (4 LI), while the SX series is mesh.
All tiny servers like the ST055 and SX060 can sync up to 12 units and only tip jars and statboards (not management statboards), while the standard servers like the ST100 and the SX101 can be used to sync up to 32 units with no limit in type at the moment.