Standard Dust Boot Brush.  Made in the USA.  Quantity is by the foot and you will receive a continuous strip of brush for your order.  Backing is approx. 3.5mm X 3.5mm with a OAL of 3.55" from top of backing to base of bristles.  Bristle diameter approx. 0.25mm.
 
***This brush does not work in Pixels to Prototype Dust Boots or the Pete Sqared Dust Boot***