These mills feature the innovative u Select system. u Select mills have the same renowned grinding mechanisms beauty and functionality as classic Peugeot mills with an additional feature of easy grind selection. When you want to adjust the grind of your salt/pepper to more coarse or fine you simply turn the u Select ring at the base of the mill. You can select one of six pre-marked positions or any point in between for infinite possibilities. Your selection will not move or change until you want it to. To get the best out of your Peugeot salt grinding mechanism you should use: dry salt ideally with a diameter of 4 mm ( 0.16 ) such as coarse sea salt or rock salt (salt mined from an underground salt seam). Do not use your Peugeot salt mill for grinding pepper or any other spice or damp sea salt (also known as grey salt Guerande Re etc. ) The moisture content is so high in damp salt that it will corrode the mill. Use a Peugeot Wet Salt mill with a mechanism specifically designed for damp salt. Its shape and materials have been designed to resist salt corrosion.