TIPS. For keep your robotrunning at forperformence, please changing the the consumable replenishmentevery 2~3 months, depending on your use frequency. and . These replacement parts are nylon brushes, which can remove dirtand trash in corners and edges, easily clearing up housework keep the floor . EASY TO REPLACE. Simple installation,otherrequired. Perfect repair accessoty for llife series robot . Package includes: 2 Pieces ReplacementBrush