The Lipstick Brush with Plastic Case from Dot Line is a compact, retractable soft brush designed for removing surface dust from cameras and lenses. The brush includes a protective plastic casing to prevent the bristles from acquiring unwanted debris.
Only one caveat: turn the brush parts to open it; Do not pull them apart; that damages the bristles, as most any woman can tell you because these camel hair brushes are also used for makeup ... where they cost a million (or less)
Generic, simple, used a lot when my cameras were out in the Southwestern desert, recently. I have one in each camera case and in my cleaning kit.