All solid spherical bearing mounts increase suspension accuracy and allow for High KG rate springs. Equipped with 20 KG front and 16 KG + 3 KG helper rear springs. This is intended for extreme fitment applications where you want to ride extremely low without hitting the ground when driving through dips. The helper springs add down travel for traversing driveways without teetering on 3 wheels. 12 click damper settings range from extraordinarily stiff to a compliant but firm ride. You can upgrade to an air spring at any time for a $1000 option cost. However if you opt for air springs during your initial purchase, we will install them for free in lieu of supplying the coil springs. Thoughtfully designed rear upper mount has 2 different mounting positions, one farther out from the chassis to achieve the extra clearance required for the (larger diameter than spring) bags while the inboard position is intended to give more clearance for wide wheels whn using coil springs. ***Advisory*** These are required when using our rear arm set because the aftermarket RLCA does not support to Frame OEM type spring. Coilovers and bag-over-dampers are compatible with an otherwise stock suspension (if you don't lower it very much). However if you desire more than a little ride height change, or you want to fit aftermarket wheels, that can only be aligned with our arm set. The spring rates supplied and dampers set to hard rides extraordinarily stiff whereas the air springs provide a ride more similar to the OEM feel.