[Solanum]

I would imagine it is a GSO one (the picture on the MAS website looks exactly like a GSO one), same as Bintel, Andrews etc. sell. I have the standard GSO Barlow and I don't like it. I did see someone else on here claim that there was no difference between the ED and standard GSO Barlows, but I would hope that is incorrect as they are sold at different prices.

I don't have a decent Barlow so can't recommend one, but as you would use it with multiple eyepieces I would say buy the best you can get otherwise you are limiting those eyepieces that you use it with.