Billiard table manufacturers have produced convertible billiard tables (in the broad sense) that double as dining tables or as table tennis, foosball, or air hockey, tables, with removable hard tops. Home pool tables, which often lack a ball-return system, are commonly either 4 × 8 ft or 3.5 × 7 ft models, a medium between 3 × 6 ft. bar/pub tables and 4.5 × 9 ft tournament-size models. Low-end tables tend toward the smaller range, and may have MDF or wood beds as an alternative to slate; those with light-weight beds may be foldable for storage, as with table tennis. Miniature tables
Billiard table the nap. , also known as (for their traditional shape), are inlaid at precise, evenly spaced positions along the rails of some tables (not usually on snooker tables) to aid in the aiming of bank or kick shots. There are seven along each long rail (with the side pocket interfering with where the seventh one would go, on pocket billiard tables) and three along each short rail, with each of the four corners counting as another in the mathematical systems that the diamonds are used to calculate. These sights divide the playing surface into equal squares. Books, even entire series