1., pay attention to the place of production. Under normal circumstances, the local product quality is well protected by strict supervision.
2., pay attention to ordering in advance, not in stock. General filters will not exactly match your requirements. Who says there are lots of stocks, most of them are lying. It's not a product that can't be sold. In this case, it is more impossible to buy.
3. ask the salespeople about technical issues. To judge whether the product is professional.
4., don't trust words and materials. Good quality is the absolute principle.
