Hollow strap-on extensions are very easy to use. How you use the strap-on extension depends on the type of harness system. The most common is a waist harness made from comfortable elastic which allows it to universally fit most body types. Place the harness on your body as it was designed by the manufacturer. Once the harness is in place, add a bit of water-based lubricant to your penis as well as the inside of the dildo. Once you are lubed up, slide your penis into the hollow portion of the dildo. From here, you should be ready for enjoyable penetrative sex with your partner. If you have a penis place it inside the hole. If you do not have a penis skip this step. Tie, lace, or buckle the harness around your body so the strap-on dildo stays erect as a penis would naturally. Place a water-based lube on the toy and on the person receiving it. Have fun!