The outer layer is made of hard abs material and the inner one is made of glass, which is protected by a double layer. Additionally, the colored textured top caps are firm and durable, ensuring it won't easily cut your children's hands. The sand timer helps your kids do things more efficiently and develop a strong sense of time. It can be used for cooking, games, classrooms, study, office desk decoration, and by teachers. There are 1/2/3/5/10/15/45/60 minute options to choose from. Customization is available.