The Magni Focuser is of US origin and the Geoscopes are Australian Made. Most modern lenses are made from plastics, especially acrylic, polystyrene and polycarbonate.
Plastics are lighter and tend to transmit more light than glass.
Furthermore, optical corrections are more easily accomplished using various plastic elements. Geoscope - Mirror Stereoscopes Used by students and professionals in geology, geography, surveying, archaeology and the earth sciences around the world for its high quality and affordability. The design award winning Geoscope is constructed from tough and durable ABS plastic and has chrome surface mirrors and crown glass lenses making it suitable for the rigours of class rooms, field and office work. The use of high quality mirrors and lenses ensures superior images but at a fraction of the cost of its competitors. Tough, durable ABS plastic for all parts.