The 80mm Front Ring - Extension is a unique solution for lens setups that require a bit more space between the filter threads of the lens and the matte box or filter attachment. Available in several sizes, the 77-77mm models will essentially extend a plain 77mm filter thread by 1" or 2". The 60-77mm x 0.5 model is ideal for use with the Leica R 35-70mm f/4.0 lens which requires a slightly longer step-up ring in order to accommodate full focus and zoom travel. Machined from billet aluminum and anodized black with a threaded inside surface to reduce reflections.