Everyone probably already knows this, but I didn’t until a few weeks ago.
The Blue tabs on fans on the NX3132Q-V Std Air, means the fan side should be in the cold (blue) aisle (symbols on the tab show air being sucked in.)
The Red tabs on fans on the NX3132Q-V Rev Air, means the fans blow hot air out the back and should be in the hot (red) aisle (symbols on the tab show air being blown out.)
Most commonly, the NX3132Q-V Std Air is used for the NetApp ONTAP cluster switches, since it makes the cabling easier (the ports at the back of the controllers are the same side of the cabinet as the switch ports.)
Image: Cisco Nexus 3132Q-V Std Air with Blue Tabs on Fans
Image: Cisco Nexus 3132Q-V Rev Air with Red Tabs on Fans