H&R Sport Springs are designed for a lower center of gravity, improving handling and giving the car a more aggressive appearance. H&R Springs are wound from 54SiCr6 spring steel that is extremely strong and resilient. They're claimed to be "lighter and more durable than other automotive coil springs."
Lowering is rated (by H&R) at 1.0" front, 0.75" rear for 2002-06 coupes, 1.4"/1.4" for convertible models, and 1.4"/1.4" for 2007+ models. For what it's worth, we measured about 1.25" of lowering on our '07 Cooper S.
Set of four springs. Fits 2002+ Mini Cooper and Cooper S.