Ideal for promoting the principals of flowing water in nature and science. Water can be moved by opening and closing the taps on the top two tray, and then pumped from the bottom tub back into the top tub. Set includes 2 x water tubs with tap system, 1 x water tub fixed with clear tubing to recycle water back into top tray by using the squeeze ball pump. Complete with sturdy metal stand with two castors.