All Authentic N95 respirators will have the following features:

Headstraps: NIOSH approved N95 respirators use 2 headstraps to attach to the face instead of earloops. Headstraps ensure that there is a proper seal around the nose and face. 

Stamp: Every NIOSH approved N95 respirator has a stamp that contains the NIOSH symbol, the model number of the respirator and a NIOSH supplied approval number. This approval number can be looked up in the official NIOSH database. If a respirator is not in this database, it is fake.

Lot Number: NIOSH approved N95 respirators contain a lot number provided by the manufacturer. The lot number can be found either on the mask itself or the box. This lot number is maintained by the manufacturer and allows NIOSH to track all N95 respirators in the market and ensure that they have undergone proper quality control.