The K&F Concept ND2-400 Variable Neutral Density ND Filter is a high-quality circular filter with a blue colour, designed to provide neutral density effects for digital cameras, camcorders, and other camera equipment. The filter is threaded for easy mounting and has a 77mm filter size, making it suitable for a wide range of photography and videography applications. Manufactured by K&F Concept in China, this filter comes with a 1-year manufacturer warranty, ensuring its quality and durability for professional use.