Certain examples described herein relate to a removable unit for a three dimensional printing system. The removable unit comprises at least one compartment to store build material for a three-dimensional print job, a coupling to engage with a printer device of the three-dimensional printing system, and a memory. The memory is configured to store instructions for the three-dimensional print job for the printer device, and the instructions are readable from the memory by the printer device when the removable unit is engaged with the printer device.