Blue Ginkgo Silicone Stacking Cups – Nesting & Sensory Stacking Toy For Toddlers | Open-Ended Montessori Toy With 5 Cups (Pastel Colors)Build It Up And Knock It Down. Silicone Rainbow Stacking And Nesting Cups Are Durable, Versatile And Ideal For Open Ended Play, Helping Little Ones Work On Motor Skills And Color Recognition Through Play. Made From Durable And Soft Silicone, This Set Of Children'S Stacking Cups Is A Modern Plastic Free Alternative To The Classic Toy Stacking Cups That Have Become An Essential Toy For Every Family With Young Kids.