Introduce infants and toddlers to auditory, visual and scientific effects of gravity and friction using Jumbo Tracking Tubes. The thick acrylic tubes are reinforced by soft-touch, over-molded Poly+ end-caps and filled with contents ranging from static-sensitive foam, to shiny and colorful pom poms, to various geometric wood and metal trinkets. Bring sensory experiences to life with this toddler-safe set. Each tube measures 2.4" Dia. x 18.5"H .