This product uses the pulling and inserting structure. When used, the lens should be pulled out; when not used, the lens should be inserted in the outer bags to avoid any friction, as it can protect the lens effectively and prolong its life. The lens can be changed freely by lens bracket or raise battery active covers. The lens bracket terminal uses the bulge handle or the hollow handle to make the operation more conveniently. It uses Fresnel lens which have high enlargement rate, to make the whole item ultra-thin and have a large enlargement sight.