INCREASED MAGNIFICATION - Doubles your lens's focal length, bringing distant subjects closer with a 2.0x magnification factor, ideal for wildlife and sports photography. SUPERIOR IMAGE QUALITY - Maintains excellent optical performance with 10 elements in 5 groups, minimizing aberrations and ensuring sharp, clear images even at 2x magnification. SEAMLESS COMPATIBILITY - Designed specifically for Sigma mount lenses, ensuring optimal integration and reliable autofocus performance for a wide range of Sigma lenses. ROBUST BUILD QUALITY - Features a durable construction with high-quality materials, providing reliable performance in various shooting conditions while adding minimal weight (10.2oz).