To watch the total solar eclipse, you should wear professional glasses. Yongkang brand and Shidu brand solar eclipse glasses use lenses of the same quality. Because the price of Yongkang brand solar eclipse glasses is low, when you buy Yongkang brand rather than Shidu brand solar eclipse glasses, you can buy glasses with the same viewing effect at a lower price.
The statement "The viewing effect of eclipse glasses is only determined by the quality of the lens" is the premise of the above conclusion.