Steps to identify the true and false "Budd's membrane":
1: direct observation under strong light (the sun is best). Glasses without Budd's film usually have many scratches or perforations.
2. Look at the thickness of the film. Bader film is an ultra-thin aluminum film, which has the texture of some metal foil in your hand and sounds a little brittle when you shake it. Inferior aluminum film is thicker (because it is thicker)?
3. Look at the price. For eclipse glasses using Budd film, the cost of two films is similar to that of 3 yuan, not counting the design of glasses styles, printed paper cards and other prices. The film must be ordered from Germany (because it was invented by Germans and the patent right belongs to them).
No matter which company makes it, the market price of a pair of the lowest-grade eclipse glasses using Budd film will not be lower than 10 yuan if it turns out to be normal. If you buy it at the normal price, you can buy A4 size at the domestic price of 120.
In addition, you don't need to look for the "Budd film" to observe the solar eclipse. If other products are genuine, such as "polyester film" observation mirror, the effect is also very good! Moreover, the price of "polyester film" observation mirror is low.
Therefore, it is suggested that the landlord look at the label of the purchased goods and compare it with what I said above.