Whole hops (sometimes called "leaf hops" or "raw hops") are dried, cone-shaped flowers from the female hop plant. Whole hops are often used in dry hopping, as they are easier to remove from the beer and may give a slightly fresher aroma than pellet hops, which lose some of the flower's essential oils during the pelletization process. Pellet hops are produced by grinding up the whole hop cones and pressing them into pellets. When used for bittering, pellet hops have a higher extraction efficiency by weight than whole hops (about 10% more). For reference, 1 oz. of pellet hops yields ~10% more IBUs than 1 oz. of the same hop variety in whole form.