This is a great material to enhance your child's hand-eye coordination, and his ability to discriminate between small and large sizes of the same object. It also teaches your child the horizontal twisting motion. Let your child tune their fine motor skills and also hand and eye coordination with this practical life material. In Practical Life, Bolts and Nuts gives the child opportunities to master the skill of opening and closing nuts and bolts; to reinforce hand-eye coordination ability; to enhance concentration level. In Sensorial aspect, Bolts and Nuts helps in the development of visual discrimination of sizes of the same objects. Learning the proper use of tools is an important part of the Practical Life skills, and the Nuts & Bolts materials are an excellent way to develop hand-eye coordination and fine motor skills.  Set A consists of a wooden frame measuring 30 cm x 8 cm x 7 cm high (about 12" x 3" x 2.5") and another board, each with seven different sized holes in them.  Seven different sized stainless steel bolts and nuts are provided for the student to match together and use to affix the board to the frame.  This exercise can be done with hands only, and does not require any tools. The Montessori Screw Nuts Block is composed of a solid wooden block with 7 different holes aligned in a horizontal position. It comes in a beautiful and natural light brown color and silver metal nuts and bolts. The block also comes with a detachable wooden plate for children to attach it to the fixed block using the different bolts and nuts.  Each hole is a different size arranged from the smallest to the biggest, so it is consistent for the child to discriminate the different sizes. This Montessori material comes with a base, so it can be easily manipulated by the child and seen from different perspectives when they are discriminating which bolt matches each hole. - Eco-friendly, 100% meet the stardard of the international REPORT EN71-3, ASTMF-971, follow the AMS & AMI standard - The product could use at montessori kindergarten or homeuse for early learning development, or occupational therapy - Nothing goes into the mind that does not first go through the hands Caution: choking hazard due to small pieces.  Not recommended for children under 3 years old.