Material and workmanship, locks prices ranging from ten dollars to several hundred dollars, A grade, B grade, ultra-Class B market locks lock cylinder is divided into several. Consumers to identify the lock cylinder can through the billiard row number how many good or bad. In general, multi-row the tumbler lock tumbler lock better than single-row, multi-row invisible tumbler lock is better than ordinary multi-row spring lock. According to Jiangnan hardware store manager, the cost of the B-level lock cylinder is much higher than the A-level lock cylinder, therefore, most of the locks in the market launch of the brand's products are Class A lock. Security door key if there is only a row of marbles, basic A-level lock cylinder. If you feel safe enough to replace the Class B or ultra-Class B lock cylinder to improve the performance of the overall anti-theft security doors.