First recommendation of the dentist: the two-minute brushing time of the hourglass teeth is designed in accordance with scientific knowledge, and does not give children the feeling that time is too long and they lose interest in brushing teeth Cleaning assistant: fun colour designs and cute tooth shapes as well as cartoon smileys make children fall in love with brushing their teeth Safety material: made of durable PVC, high borosilicate glass, non-toxic sand, very safe for children. After testing, the base at both ends is not easy to pull out and not easy to break, which is an ideal timer for children to brush their teeth MULTIPLE APPLICATIONS - Very suitable for children to brush their teeth, also can be used when learning or playing to help children do things more efficiently and improve the concept of time. A great gift for children and friends Instructions for the hourglass: you will receive 2 hourglass for 3 minutes. Please shake the hourglass to release all the sand and turn it on the table to start the clock. For non-precision meters, please allow 10% time deviation