This set of four colourful wooden nuts and bolts is an excellent way to help develop fine motor skills by grabbing, twisting and turning. Each of the four bolts can be screwed into any of the four nuts, and the completed structures range from 7 cm to 9 cm (2.5" to 3.5") tall. All of the pieces are finished with water-based, non-toxic stains, and are completely safe for mouthing.