Evidence of altered dice can be used by the prosecution when State statutes have separate offenses for "crooked games" or when the court admits the evidence to prove aggravating circumstances. Investigators working under field conditions, with a minimum of study and practice, can detect most common types of alterations. One type of alteration is the misspot, when dice are made so that all six numbers are not represented and all pairs of opposite sides do not equal seven. Dice may be loaded by removing part of the plastic material and substituting a heavier substance, usually lead, or by inserting a magnetic substance. In other alterations, dice are made flatter (flats or bricks) or rounder (rockers or bevels) than ordinary dice. Crooked dice may have edges that are not sharp, not at 45-degree angles, or filed to have an increased area.