Burr mills use two revolving abrasive elements, such as wheels or conical grinding elements, between which the coffee beans are crushed or "torn" with little frictional heating. The process of squeezing and crushing of the beans releases the coffee's oils, which are then more easily extracted during the infusion process with hot water, making the coffee taste richer and smoother. Both manually and electrically powered mills are available. These mills grind the coffee to a fairly uniform size determined by the separation of the two abrasive surfaces between which the coffee is ground; the uniform grind produces a more even extraction when brewed, without excessively fine particles that clog filters. These mills offer a wide range of grind settings, making them suitable to grind coffee for various brewing systems such as espresso, drip, percolators, French press, and others. Many burr grinders, including almost all domestic versions, are unable to achieve the extremely fine grind required for the preparation of Turkish coffee; traditional Turkish hand grinders are an exception. Conical burr grinders use steel burrs which allow them to grind effectively while rotating relatively slowly, usually below 500 rpm, reducing frictional heating of the ground coffee, thus preserving maximum aroma. Conical burr grinders are quieter and less likely to clog than disk grinders. Grinders with disk-type burrs usually rotate faster than conical burr grinders and warm the ground coffee a little by friction, manual models less than electrical. They are cheaper than conical burr grinders, and are well suited for grinding small amounts of coffee (with no time for heat to build up) for home use. A burr mill or burr grinder is a device to grind hard, small food products between two revolving abrasive surfaces separated by a distance usually set by the user. Usually the device includes a revolving screw that pushes the food through. It may be powered electrically or manually. Devices with rapidly rotating blades which chop repeatedly (see food processor) are often described as grinders, but are not burr grinders. Burr mills do not heat the ground product by friction as much as blade grinders, and produce particles of a uniform size determined by the separation between the grinding surfaces. Food burr mills are usually manufactured for a single purpose: coffee, pepper, coarse salt, spices, or poppy seeds, for example. Coffee mills are usually powered by electric motors; domestic pepper, salt, and spice mills, used to sprinkle a little seasoning on food, are usually operated manually, sometimes by a battery powered motor.Turkish coffee is a method of preparing coffee. Roasted and then finely ground coffee beans are boiled in a pot (cezve), usually with sugar, and served in a cup where the grounds are allowed to settle. This method of serving coffee is found in the Middle East, North Africa, the Caucasus, and the Balkans.