this be my favorite bottle brush because it stand up and it have a sponge at the end , not bristle . I think this be one of the only brand with that combination . brush with only bristle at the tip make a big splashy mess . I can not seem to use they without liberally spray everything within 6 foot when I wash the bottle . yeah , these brush do not last forever . neither do my kitchen sponge . I have be replace these every 3 or 4 month . I think that be a decent lifespan for something that be use multiple time a day , every day . go Dr. Brown .