Dedicated overland travel requires unique spring rates to handle heavy loads and continuous mechanical resonance compared to standard coil spring rates. That–s why we paid special attention during spring rate tuning and development of our Outback Lift Coil Springs. All this adds up to our load-enhanced heavy-rate coil springs that meet the demands of a fully loaded Jeep while maintaining advertised lift height. TeraFlex JK: Lift Coil Springs are perfectly engineered for your JK Jeep Wrangler/Unlimited. Our engineers focused on extensive rate tuning and dynamic balance between front and rear load bias to produce Lift Coil Springs that deliver unsurpassed highway handling and off-road performance. TeraFlex chose the same tried and true linear rate technology preferred by most automakers including Jeep. Linear rate springs provide the maximum number of active coils under load for consistent performance and predictable handling throughout the full range of suspension travel both on- and off-road. We recommend pairing TeraFlex Lift Coil Springs with Falcon Performance Shocks for superior performance. TeraFlex coil springs and Falcon shock absorbers have been engineered together to improve both compression and rebound for optimal vehicle stability.