Attaches to the front accessory thread of 645 series lenses to provide optimum shading of the lens to prevent flare from stray light. Rack & pinion adjustment allows selection of optimal setting by actual preview; incorporates 3" gelatine filter holder. For use with lenses from 55 to 300mm, except 300mm f/2.8. Supplied with Adapter Rings for 58mm & 67mm lenses. Can be used on other brand lenses with step down rings.