Package contents 1 center brush roller for Roomba COMBO series Compatibility 100% compatible with Roomba COMBO, model R1138, and model R111840 Construction and durability components designed for lasting use and reliable performance Replacement interval Typically 24 months depending on usage and environment Function and benefits Center brush agitates and sweeps dirt, hair, and debris from floors to improve pickup Helps maintain suction efficiency by replacing worn center brushes Fit and installation Sized and designed to match the Roomba COMBO center brush for easy, dropin replacement Use scenarios Pet owners dealing with shedding hair on carpets and hard floors Homes with mixed flooring, including carpets and hard surfaces traffic households requiring regular maintenance to preserve cleaning performance How to tell it needs replacement Decreased pickup performance, more hair tangling around the brush, or visible wear on the center brush Note Replacement part designed to preserve Roomba COMBO performance without altering original functionality