This fan shroud for 120mm fans is ideal for blasting a fast horizontal stream of collimated air over your delicate prints. It is meant to replace hotend-mounted fans, particularly on small printers that are unable to carry such accessories. For example, the RepRapPro Huxley. Adding a larger and more powerful 120mm fan will greatly increase results and eliminate the need for a second opposing fan. I use the 225DS-1LP13, manufactured by Etri. For mounting options, check out my vitamin-free fan mounts: http://www.thingiverse.com/thing:36300 This shroud is derived from animator75's fan shroud which comparatively has a wider and less efficient air flow: http://www.thingiverse.com/thing:290141 Observe images above for proper shroud positioning.