Safety Sandglass Timer: The mini 10 minute sand timer made by skin-friendly high borosilicate glass and acrylic material. And each one has a long-time test. This sand watch for kids is easy to distinguish which timer for which usage. Unbreakable Design: The outer layer is made of hard acrylic material and the inner one is made of glass,which is protected by double layer. Besides, the silver textured top caps are firm & durable, so it will not easily to hurt your children's hands.