Speed Stacks G4 STACKMAT - Blue Flow G4 Blue Flow Mat and G4 Pro Timer Accuracy to 0.001 seconds; Includes 2 AAA batteries Data port to connect to external display Endorsed by the World Sport Stacking Association (WSSA) Winner of a 2018 Family Choice Award! The "Family Choice Awards" recognize the best in children's and parenting products. Now in its 21st year, the "Family Choice Award is one of the most coveted, family friendly consumer award programs in the nation.