Explore the dynamics of disc height loss in this L4-Sacrum model. Includes a homogenous L5-1 and a heterogenous (annulus and nucleus) L4-5 elastomeric disc. Demonstrate stiffness at L5-1 and hypermobility with disc herniation at L4-5 in this model. Stand included. Optional cauda equina (with and without rootlets) and medial branches at L4-5 left facet