MDF Wheel, 6mm thick fibre board, 54mm and come with drilled centre holes for 4mm dowel, There are also available in 54mm and 74mm or you can order a mix bag
reflection and refraction demonstrator, 16cm diameter acrylic water tank has a 360 degree scale and a moveable arm carrying a laser activated by a push-button, Thumb screws on the side of the laser harness can be adjusted to finely position the laser beam