Focusing masks take the guesswork out of focusing and even get over the seeing conditions as it is a mathematical type approach to the task. The best focus for your telescope quickly and easily. Suitable for use on all types of telescope, reflectors, refractors. Features - Color: Black. - Size: 10.00X10.00X0.30cm/3.93X3.93X0.12 inch. - Material: Aluminum alloy. - Focusing mask is to help you focus quickly. It can help you achieve a perfect focus webcam in seconds. - Focusing mask with 3 fixing screws; they have a scratch-resistant silicone sleeve to protect your precious telescope surface from scratches. - Focusing mask is made of metal. It is very lightweight and will not become a burden to maintain the balance of the telescope - With 3 holes. The mask can be easily connected to any telescope by 3 screws. - It is manufactured with professional technology to ensure the of the product and can work for a long time.