Acrylic plate thickened design Closed grooves regular arrangement The plate surface is , flat and translucent The metal material is roughly bar-shaped and is attracted by magnets. It forms a regular and magnetic induction line. Magnetism is not , is very clear and distinct Do not contact with products such as calcium acid during use or storage, and keep it dry to avoid oxidation of metal parts and affect the experimental effect. colour: as shown Material: plastic+metal Package Contents: 1 set x Magnetic Field Lines Demo Board Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.