Tomson Bianjian's liquid calcium supplement effect is not bad, it is liquid, easy to absorb, and the loss of calcium is less wasted. I bought some for my family before, but I bought them at a drugstore, which is more expensive. You can ask the boss about the source of goods, whether his online shop is a factory agent or has its own physical pharmacy. Tomson Bianjian has many detection methods, which can be used to test the authenticity. At present, the protection of online shopping for buyers is still relatively good. You should buy with confidence. If you are not satisfied, you can return it at any time. I hope it helps you.