This dew shield is perfect for your 4 inch diameter telescope. It is made of high-quality PETG material and features a 3D printed design for optimal dew prevention. The shield has a total length of 10 inches and is compatible with universal brands and models. This accessory is a must-have for any telescope owner who wants to prevent dew and keep their equipment dry. It is easy to use and can be attached to your telescope without any hassle. Made in the United States, this dew shield is a reliable and durable solution for your dew prevention needs.