These GSO Super Plossl eyepieces are undoubtedly the best eyepieces of their category in middle-price range. The most important factor is the quality of optical elements. First of all, by using a modernised anti-reflection coating and a very accurate polishing of lens surfaces, an even better quality of view was achieved. While the average light transmission of these eyepieces is 96.4%, they produce an incredibly high 98% transmission level at the wavelenghts of orange light.
They are made by the famous Guan Sheng Optical factory (supplier of Meade and other astronomy equipment brands) in Taiwan. Some of them may have a brand name on them of TS instead of GSO.