They've historically (until this generation -- I haven't poked at our new ones) used commodity Dell servers, along the lines of a 2U PowerEdge. While they were

They've historically (until this generation -- I haven't poked at our new ones) used commodity Dell servers, along the lines of a 2U PowerEdge. While they were welded shut, it was entirely possible to wipe them and reimage with your own Linux install, provided you had a way to boot from USB. We did this with all of the previous generations of appliances after they were replaced by the new contract. They became perfectly serviceable test boxes.