The horizontal injection moulding method has traditionally been the more widely used type of injection moulding. Horizontal injection moulding involves opening and closing a mould along its length. The mould cavities are filled under injection pressure for packing and cooling within this configuration. Most horizontal moulds have more cavities than their vertical counterparts, allowing them to produce more parts per batch. In addition, since the mould halves are horizontally separated, parts from these moulds drop out of the cavity on ejection, eliminating the need for manual removal.