Speed Stacks GX STACKMAT - Rainbow Drops GX Rainbow Drops Mat with GX Timer Accuracy to 0.01 seconds Includes 2 AAA batteries 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.