The Synergy Twin benefits from SCUBAPRO's second-generation Trufit Technology. Unlike its predecessor, which featured a skirt made with uniformly thin silicone, the Synergy Twin Trufit features a skirt made of two thicknesses of silicone - thin and pliable where it touches the face for comfort and to ensure a watertight seal, and thicker near the mask frame for support and rigidity. Itâ€s an effective combination that delivers a comfortable fit for a wide range of face shapes as well as a reliable seal against water intrusion. The dual-lens design is low volume and offers a wide field of view.