What is a wonder glass? A glass full of milk is shown. Covered with a hanky for just one moment, all of the milk has then magically vanished from the glass!
Ventriloquists hold them up to their puppets with a straw in them to make it look as though their puppet friend is drinking!
Use any liquid, it does not have to be milk! Easy to use. Made in a super strong (thick and washable) plastic.