You never need to worry if you will have time to return what you purchased if you need to return a product, the only requirement is that the product is in the same condition as when you received it, new and unused.
Kegel balls are used to prevent incontinence, as well as to get a better sex life. Fit and tight pelvic floor muscles also gives us more powerful orgasms. It is an advantage to be able to squeeze active during intercourse and then stimulate both yourself and your partner. Sure you can do pelvic floor exercises, even without aid, but with kegel excersisers you are forced to really take care of your training. You can not relax or cheat, then the ball will slip out.