Natural crystals currently do not have strict international grading standards, and each market has different definitions. The following is a less stringent industry agreement. The basis for the identification is the result of visual observation without the aid of a magnifying glass, mainly for white crystals, which have the following levels:
AA level: The whole crystal is transparent inside and outside, and there is no visible artifact on the surface.
Grade A1: There are very fine flaws, or small natural inclusions, no more than 3 mm of cloud or floc.
Class A: A slight sputum, useful for clouds or batt that are easily visible to the naked eye.
Class AB: There are large cloud inclusions, small ice cracks, and small scratches on the surface.
Grade B: More than half of the crystal is cloud and inclusions, large ice cracks, and small cracks on the surface.
Grade C: The lowest level, the whole is cloud-like, the ice crack marks are obvious, and the surface also has obvious cracks, which seems to be broken at any time.
The value of crystal is also related to the crystal size. The same level, the bigger the rarer, and sometimes the lower level, but the crystal is large enough, it may be higher than the high-level small crystal. Due to the exploitation and production of natural water, crystals that do not produce enamel are difficult to obtain, or a small piece of crystal is used to make a small ornament. AA-grade products are rare, and they are the best on the market. High collection value.
Note:
- This product is a civilian mask, not suitable for use in hospitals, not a medical mask
- Please note: The mask is disposable, so return and refund are not supported
- There are few words on the mask
- All mask pictures are for reference only, and the actual product received shall prevail.
- KN95 = N95 mask
- Please be kindly noted,the listed product is produced and distributed abroad and subject to the laws of its country of origin
Features:
Made of high-quality material, safe, soft and comfortable.
It can filter out more than 95% of exhaust, dust, chemicals, particles, pollen, smoke and fumes, great for many occasions.
Elastic straps and adjustable nose clip for different face shapes and sizes. Simple steps for wearing.
By covering the mouth and nose, it prevents droplets from spreading. Effectively protects you from being infected with the virus.
Fits for home and professional use, perfect for daily use, outdoor activities
Non Medical Kn95 Face Masks,Kn95 Face Cover,4 Layers Earloop Face Masks,Disposable Kn95 Face Masks
Suzhou Ruihan Automation Technology Co. LTD , https://www.ruihansz.com