Treat your child's watch to a silicone strap for Garmin Vivofit Jr. 3, which is durable and incredibly nice.  

This Garmin Vivofit Jr. 3 strap has a good and comfortable fit, so it sits tightly around the wrist. Since the strap is made of silicone, it is sweat and water resistant, even when your child is playing sports. 

Note: Fits wrists from 130 - 140mm in circumference. (watch size IS taken into account)