Bran Muffins II

Preheat oven to 400 degrees F (200 degrees C).
In a large mixing bowl, sift flour. Add the cereal, sugar, baking soda and salt; stir to combine.
Add eggs, shortening and buttermilk; mix well.
Cover bowl and store batter in refrigerator for at least 24 hours before using. Batter will keep in the refrigerator for up to 6 weeks. Batter should remain covered and should not be stirred.
Scoop batter into lined or lightly greased muffin cups, filling each cup 2/3 full. Bake at 400 degrees F (200 degrees C) for 15 to 20 minutes, or until a toothpick inserted into the center of a muffin comes out clean.