If you are referring to the eyepiece with the large rubber 'volcano top', I have found this decent and very useful for public viewing nights. The true field of view is larger than most 28 mm eyepieces in a 1.25" barrel. The rubber cone is designed so that it is easy for less experienced viewers to have their eye in exactly the right place. People wearing glasses can keep them on and readily see the full field of view. The eye lens is large and recessed so that it will remain clean (no eyelashes grease). A good piece of kit.
