I see where people have a lot of issue and I barely purchase one because of they but I actually Love the brush . Mine have not tear up at all , I like the sponge tip for the bottom of the bottle floor . especially for breastmilk which have a lot of fat ... if you get a brush with a prickly brush head and not a sponge ... then it miss area on the bottom of the bottle floor . it will stay greasy no matter what liquid you use . . by the way , Palmolive Baby work magic and leave the bottle squeaky clean . for hygiene purpose I switch my brush out monthly as I wash several bottle daily ... I also `` after '' it dry out , I use a zip lock bag on the tip of it to keep it sterile .  Palmolive Ultra , Baby Bottle , Toy , & Dish Wash liquid 20 fl oz -lrb- 591 ml -rrb-