Pkg (20) Small Bore Brushes. 5-3/4&rdquo; Long Overall with 1/2" Dia x 1-1/2&rdquo; Long Nylon Bristles. Great for Small Bottles! These little brushes are made for cleaning tracheostomies, but they're dandy for any use on small bores. Brushes measure 5-3/4" long overall with 1/2" dia x 1-1/2" long nylon bristles. We're thinking bottle brush for baby-bottle nipples, salt- and pepper-shaker necks, and all of AS&S's tiny bottles.