1. It is necessary to choose produces of high popularity, stable quality and good after-sales service.
2. Check at first whether the identification of the purchased products packaging, logo is complete or not (including product executive standard, grade, production enterprise name, address, date of production) and whether packaging is firm or not. And the most important is whether the instruction book content matches the product or not. We should pay attention to the exaggerated phenomenon that does not tally with the facts.
3. Observe whether the appearance quality of the products, including lock end, lock body, spring bolt, lever handle, shroud plate parts and other related plate parts is complete or not and the surface color and luster of chrome , spray lacquer is bright or not, and check if these products rust , oxidize and are damaged.
4. Check whether the use function of products is reliable and flexible or not. Examine them by comparing with two or more locks. It is necessary to test the switch respectively for the inner and outer lock ends of all keys especially when choosing to buy two-way lock ends. Moreover, it is needed to test every lock three times or more to check products insurance structure situation.
5. Then, check the key bitting situation, such as key teeth. Each key should not be less than three different key teeth. At the same time, the first and the fifth teeth should be the deepest one for easy insertion and preventing being broken.