Our product (S) -4-hydroxy-D-Proline Methyl Ester Hydrochloride has these three properties: off White Powder Synthesized LabOur company Chengdu Pukang Biological Technology Co., LTD. 's products are trusted by customers.Not only can provide you with excellent and diverse products.You can also customize products to your needs.And it has very good after-sales service.The trust of customers is very important to us, and it is also one of our obligations and responsibilities to solve problems for customers.