Made famous recently by the Fifty Shades Of Grey Books, these balls have been around for many years and strengthen the pelvic floor muscles. Simply pop them in and wear them around the house or out and about. They don't vibrate or make any noise but they make those pelvic floor muscles work all day long! This strengthening is great for anyone who wants to improve orgasms and strengthen weak pelvic floor muscles due to childbirth or surgery.