ARC Hardware's weatherstrip can be fitted with either a synthetic plastic polymer or a nylon brush.
A weatherstrip is a long strip of metal that holds a seal made of a material such as vinyl, neoprene, silicone, or a nylon brush. 
This long strip of metal is surface mounted to the bottom of the door.
Ideally, the sweep should be installed so that is comes in contact with the bevel on the threshold but where the sweep will not touch the flooring material (i.e. carpet, tile) as the door swings open and closed.