This harnesses are a great way to strap on a dildo when you want someone to grind on your leg (freeing up your hands for other lovely things). Use while sitting or while lying down either with your leg resting bent upwards on the bed, or with you leaning into your partner from above.  This one comes with a 1.75" interchangeable O-ring that fits dildos that are thinner than 1.75" but have a flared base.  Put your dildo in first, then attach the harness securely around your thigh with Velcro.  Voila!  You're ready to roll!