In large mixing bowl, combine cereal, peanuts, chocolate pieces, marshmallows and raisins until well mixed; set aside.
In medium saucepan, melt butter over medium heat. Stir in sugar, corn syrup and flour. Bring to a boil, stirring constantly; boil 1 minute.
Pour over cereal mixture; toss to coat. Press mixture onto a greased 15x10-inch jelly-roll pan. Cool completely; cut into bars. Store in an airtight container.
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