This Vac U Lock 8 inch Raging Hard Ons Dong attachment fits to any compatible Vac u Lock Starp On Harness System from Doc Johnson. The Raging Hard Ons Dong fits onto the Vac U Lock plug supplied with your origianl harness. This Realistic Dong is soft to the touch and heavily veined for improved intensity during use. It is now made using Sil-A-Gel from Doc Johnson, making it anti bacterial, non toxic, latex and cadmium free.