It's been proven that strong pelvic floor muscles can contribute to a healthier sex life, increased sensation, and stronger orgasms. Teneo Duo's are round, weighted silicone balls with a gentle criss-cross texture that are designed to work out these special sex muscles; you'll need to squeeze and flex the pelvic floor to keep them in place. Once you've mastered control, you can take things a step further into pure pleasure, since any movement will make the Duo's vibrate gently. You can keep them in place as long as you like, even during everyday activities. The hygienic silicone material is easy to clean and sterilize, and is body friendly and hypoallergenic. Always use a water-based lube with the Smartballs; a sample is included. Specifications Length - 4 1/2" Insertable length - 4 1/2" Girth - 4 1/2" at largest Material - Silicone, plastic Special features - Discreet and wearable, hygienically superior, lube included