The characteristics of a safe, portable and accurate spinal stiffness testing device are described in this report. Because judgements of spinal stiffness made using manual tests have been shown to be unreliable, several mechanical devices have been designed to measure posteroanterior (PA) stiffness. One major limitation of these devices has been the inability to transport them to locations where subjects with spinal pain could be easily accessed and measured. This paper reports on the design and fabrication of a new, portable, mechanical device for measuring PA stiffness in the lumbar spine. Information regarding the safety features of the device, and contraindications for its use are provided.