This is an inexpensive rescue training tool for guards and emergency rescuers. The rubber diving brick will not harm the pool bottom or sides due to its rubber composition. This brick is practically indestructible. These bricks should only be dropped carefully in the pool and should never be thrown. Features:. Rubber diving brick. This brick is practically indestructible. This is an inexpensive rescue training tool for guards and emergency rescuers. These bricks should only be dropped carefully in the pool and should never be thrown Dimensions: 3.5"H x 3.5"W x 8.75"D. Material(s): rubber