This brush has a 0.012" stiff nylon bristle with a Delrin (Acetal) handle. The nylon fill material is hand-laced with nylon twine into its handle for maximum fiber retention. It's great for use in tight, narrow areas in applications where losing a bristle could create a problem. This high-quality brush has a 3 x 11 row configuration, with a 7/16" trim and a brush face of 1-1/4" x 5/16". These thin-faced brushes are popular for cleaning, scrubbing, wiping, or dirt removal in delicate applications. Autoclavable for cleanroom, sterile, or medical applications.