This is the main fan unit for the Mac Pro late 2013 model. The fan is housed within the exhaust assembly and to access the fan you will need to partially disassemble the assembly to remove it.
Please note that the roof is held in place by very strong double sided tape, this product comes with a new roof and tape kit to carry out the repair.
This is a brand new product. In some cases, new service parts come from dis-assembled new computers or larger assemblies.