Duo CO3 Balls provide a great-feeling object for the pelvic muscles to grip during Kegels- you'll have to flex to hold 'em in place, and what do you know... there's your workout! Satisfyer has provided some illustrated exercise positions for you to try, but you can also simply stand or walk around the room. Identical in shape, sexy silkiness and handy looped retrieval cord, the CO3 balls differ only in weight. The lightest blue version, at 2.2oz/62.4g is a perfect start point to kegel practice. It'll provide the least resistance and require the least amount of 'flex' to keep it in place. If you find the blue balls a breeze, you can move on to the medium pink set at 2.8"/79.4. The red balls are the heaviest, at 3.4oz/96g, and will be a great incentive to work up to. Use a little water based lube for easy insertion. Balls measure 6" (15.6cm) in total length. Approximately 3" (7.6cm) are insertable. Each ball is about 1.25" (3.2cm) in diameter