Black PVC Corset Underbust Steel Boned Corset Black Patent PVC Steel Boned Underbust Corset with Zip Front Heavy Duty Steel Boned PVC Corset Lace up Over Bust Corset Top Drawer Black PVC Corset Underbust Steel Boned Corset. This is a glossy black patent PVC underbust corset with a front zip closure and serious structure built in. You walk in cinched, and the whole room feels it before you say a word. Twelve steel bones, four static in the back and four static in the front with eight spiral bones running through the body, hold their shape through every move you make. The kind of piece you plan a night around.