Modern fryers feature a basket to raise food clear of the oil when cooking is finished. Fryers often come with features such as timers with an audible alarm, automatic devices to raise and lower the basket into the oil, measures to prevent food crumbs from becoming over cooked, ventilation systems to reduce frying odors, oil filters to extend the usable life of the oil, and mechanical or electronic temperature controls. Deep fryers are used for cooking many fast foods, and making them crisp.