A cue ball that, due to embedded iron content, is responsive enough to a strong magnet that a modern coin-operated bar table with a magnetic ball-return mechanism can distinguish and separate the cue ball from the object balls. Magnetic cue balls are usually the same standard size as the object balls in the set, and near regulation weight, typically 0.5 to 1 ounce (14–28 g) heavier than the object balls. As such they do not suffer the playability problems of either excessively dense, ceramic "rock" or notable oversized "grapefruit" cue balls, and demonstrate only minimal smash-through. Magnetic balls are standard equipment in some leagues, including the VNEA. Magnetics come in three construction types of iron embedded in the same phenolic resin or other modern, resilient plastic that the object balls are made of: a solid metal core (prone to being off-center and not rolling true); small metal bars distributed around the interior of the ball (the most common, and less prone but not immune to balance defects); and tiny metal filings throughout the material (the most consistent, only made by one manufacturer, and expensive).