Fully Ventilated Goggles with Bulletproof Lenses that Feel Like Sunglasses. The Leatt Velocity 4.0 MTB X-Flow goggle brings a whole new level to goggle ventilation. It has specially designed vents on the top and bottom of the goggle frame and lens as well as a unique mesh strap which ensures helmet ventilation still functions even when covered. The goggle features the RideViz lens. A three-layer laminated, anti-fog, bulletproof, and anti-scratch lens which ensures you have clear vision and the best protection for your eyes, along with great looks and the perfect fit, all this at a price that won't break the bank! Bulletproof 170° WideVision RideViz Mirror (Iriz) Lens. Permanent anti-fog function built into the lens. Triple-layer, dual-density comfort face foam and anti-sweat fleece backing. Self-draining open lower frame design allows dirt to fall from lens.