Stefan Mileschin

Noctua did not venture to break any cooling records with the
NH-L12 but rather to give HTPC and small form factor users a quality
cooler and this goal was reached. With just a single NF-B9 92mm fan the
NH-L12 stands at just 66mm and Low Noise Adapters make this an ideal
package for replacing that stock fan in any configuration. Noctua's
SecuFirm2 mounting system makes installation a snap and holds the NH-L12
securely in place. A premium package gives you everything you need for
installation including hardware to mount an unused fan in your case,
that is going a step beyond in my book.

http://www.overclockersonline.net/noctua-nh-l12/