KINGOU Wooden Unlock Ring Lock Wood Knot Locks Logic Puzzle Burr Puzzles Brain Teaser Intellectual Assembly Toy Material: Rubber wood. Size: 5.6 x 5.6 x 5.6 cm. Recommended for ages 5 & up, children should be used under adult supervision, water-based paint, touch smooth. Shipped by USPS, usually delivered in 15 working days. To make it challenging and fun, parcel without paper instructions, if you need solutions, please contact us.