We don't know. Manufacturers tend not to reveal ED glass type. In this instance, the manufacturer is United Optics. They say, "The ED glass is equal to FPL-53". So that is what we say on our product page.
As you know, the glass used for the ED lens is only one part of a large equation. It alone does not determine the quality of an image or the telescope's APO performance. Other factors include the mating lens, the optical figuring of the objective surfaces, lens design, the lens cell and the telescope's f-ratio. The brand and supplier's reputation must also be considered when looking for performance indicators.
StellaMira is our brand. We are the supplier. No other version of this telescope has better optics 🙂
HTH,
Steve