door kick plates
ginsberg scientific 7 200 3 1 brass ball solid
a great introduction to expansion and contraction this unit demonstrates the expansion of metal when heated and its contraction when cooled when either the ball or ring is heated the ball will not pass through the ring but when cooled the ball passes through the ring freely the ball is mounted to insulated wooden handles to protect hands from the heat american educational products have a lead ship time of 21 days sku amed2655