2005-2011 Cadillac STS Electronic/Magnetic Ride Control Struts (x2)- a type of shock absorber; has metal tubing filled with gas-charged hydraulic fluid that is connected to the wheel of a vehicle in order to reduce the effects of vertical travel on a rough surface which controls the bounciness, and therefore comfort, of a vehicle. The Cadillac Devilles struts, while having coil-springs, use an electronic signal to stiffen or soften the dampening of the strut. Some models came with Magnetic Ride Control, which use polarized particles within the hydraulic fluid to either make the ride softer or more firm based on the electrical impulse sent from the suspension control module.
2005-2011 Cadillac STS Coil Springs (x2)- Coil springs hold the vehicle up but be careful, they are rated for and designed to work with the rest of the suspension system, so when you change air shocks to passive shocks, then you will need a different rated coil spring that works well with the new type of shocks.
2005-2011 Cadillac STS Suspension Control Module- a computer which is responsible for the operations of the air suspension system and maintaining the vehicles correct ride height.