The 444s are traditional shocks in that they slide over a stud on the frame and are held in place with a bolt. Progressive touts these as their "best" shocks (in the range of good, better, best), and although the spring and rod are still made of steel, the shock bodies are aluminum, and sport a new sleeker look, with a one-piece rather than a welded eyelet, and less weight (Progressive says 4 lbs less) than previous versions. Inside is Progressive's new FST technology (Frequency Sensing Technology -- everybody's acronym-addled these days) which according to Progressive, "dynamically adjust[s] damping as you ride" to help separate wheel movement from chassis movement. (Check their website for a better explanation than we could possibly give here). Our pair came in black, but the shocks are available in chrome, too, and in 1/2 inch increments for sizing.