Proprietary soft rubber material featuring fibreglass reinforcement that overlays a durable plastic base. The outer rubber material floats on the plastic base, allowing you to twist the plug into the exhaust creating a leakproof seal. The Twin Air lanyard attached makes it easy to find and store. Offered for 2 or 4-stroke exhaust systems. Features: Outer rubber material floats on the plastic base and allows you to twist the plug into the exhaust creating a leakproof seal. Soft rubber material featuring fibreglass reinforcement that overlays a durable plastic base. Twin Air lanyard attached makes it easy to find and store. Two-stroke option fits 18mm-40mm exhaust tips. Four-stroke option fits 27mm-50mm exhaust tips. Mini option fits 18mm-21mm exhaust tips. Sold individually.