Seismic Defcon Barrel Bushings are in at ESS! Seismic’s Defcon ultra-high-rebound urethane has a remarkable set of unique and highly-advanced properties – and now they've applied it to bushings!Available in five color-coded durometers and two precision-fit heights, Seismic's Defcons make for a deeper lean and truer, more fluid steering with less lateral hanger slop.