1. Choose products from companies with high reputation, stable quality, and good after-sales service;
2. Check whether the signs and signs of the purchased product packaging are complete (including the product's implementation standard, grade, manufacturer's name, address, and production date), whether the packaging is firm, and whether the contents of the instruction manual are consistent with the product;
3. Observe the appearance and quality of the product, including whether the lock head, lock body, lock tongue, handle, cover plate parts and related accessories are complete, whether the surface color of electroplated parts and painted parts are bright and uniform, and whether there are signs of rust or oxidation and damage;
4. Check whether the use function of the product is reliable and flexible. Two or more products should be selected for comparative inspection. Especially when purchasing two-way lock products, all keyed padlocks must be used to test the inner and outer locks respectively. The insurance agency of the product should also be checked, and it is recommended that each lock be tried at least three times;
5. Check the tooth pattern of the keyed padlocks. For example, if there are five keyed padlocks, each keyed padlock should have no less than three different keyed teeth. At the same time, the first tooth and the fifth tooth should not choose the deepest keyed tooth. Keyed padlocks are pluggable and not easy to break.