The Progressive Dynamics PD306 Prismatic Lens is a direct OEM replacement lens for 750 Series and 760 Series lights. Includes two prismatic lenses per package. Progressive Dynamics, is a privately owned corporation, established in Marshall, Michigan in 1964. Its initial product was a high-quality LP gas regulator manufactured for use in recreational vehicle heating and cooking systems. Since 1968, PDI has been producing power converters and battery charging systems for the RV industry.