30mm fan guard with anti-backwash

A fan guard (for the inlet side) with anti-backwash blades for 30mm fans. Helps prevent air spilling where it shouldn't.

I use these for the fan on the extruder heat break with these fans

http://www.aliexpress.com/item/2-Pieces-Lot-12V-2pin-30mm-x-10mm-Mini-Small-Brushless-DC-Cooling-Fan/32335064214.html