Pack of 12 Yellow 24mm Magnets. Pack of 12 Strong Yellow Round Magnets by Janrax.Yellow Plastic Covered Magnets. 24mm Diametre and approx 7mm thick Ideal for Magnetic Whiteboards, Fridges and around the home and office. These magnets are designed to be strong, making sure that they will not slip or come loose from the board on their own accord. Colours are great for colour coding. A range of colours available from the Janrax range.