This is marketing gobbledygook and Streamlight should be ashamed of themselves. "C4" is short for "controlled collapse chip connection", an industry standard method of attaching electrical components to circuit boards.
C4是controlled collapse chip connection的縮寫。(對！四個C開頭的字嘛。)
說的是一種工業製程，一種把電路元件(像是LED等的東西)，焊接到電路板上的程序。
So instead of "C4" being any specific LED or LED technology, Streamlight is advertising the method used to solder the LED down.
所以，Streamlight所謂的C4 LED，並不是專指某種特定型號的LED。(事實上，從成品來看，Streamlight採用了好幾個不同型號的LED來用。)
C4 LED應該只是說，Streamlight用controlled collapse chip connection這種製程，來把LED裝置到電筒上面去，如此而已。
