Take the stack of marbles and try to place them all in the opposite column. Only one ball will fit in the sliding transporter at a time, and the order of balls in each column changes the number that will fit. Stacker is a challenging but intuitive pocket-sized puzzle that is fun to fidget with and is related to other N-ary puzzles of its type.
Small pieces; not intended for children. Item measures about 80 mm by 70 mm by 15 mm. This item is 3D-printed and handmade so expect minor imperfections. Comes in a random solid colors.