Tricky building set with different tilted blocks. Only the matching colours will complete a rectangle. All 6 blocks within one shade of colour (blue/red/green/yellow and purple) have the same tilt angle and therefore will also complete a rectangle. By building and playing with the uneven blocks, children develop fine motor skills and spatial thinking skills. 30 building blocks in a wooden frame. Materials: lime wood, non-toxic water based color stain/non-toxic plant based oil finish. Size: frame length 31cm, single blocks 6cm thickness.