120mm Biohazard fan grille
This is a 120mm fan grille with a biohazard symbol. The original symbol is from http://www.thingiverse.com/thing:7404.
I used this with my 3D printer box, more details here: http://www.igorkromin.net/index.php/2013/05/26/a-clear-acrylic-box-for-the-portabee-3d-printer-part-1-making-the-box/