The stopper in the first-floor bathroom was broken, and combined with the need to avoid cleaning out the occasional hairball (trust me, it's not mine), led us to find this combo solution at Home Depot. It comes with two threads (3/8 in. and 5/16 in.) to match different-sized drain shoes. You take care of any built-up hair by repeatedly pressing up and down on the top, which rips the hair into pieces that easily flow down the pipe without causing a clog. Pretty cool.