The ice is called a "curling sheet". It is a rectangular sheet of flat ice, between 146 and 150 feet (45-46 metres) long and 14.5 to 15.5 feet (4.4-5.0 metres) wide. The house, or target, is marked at the end of the sheet by coloured rings. The rings help players to aim for the centre of the house. They are also useful to decide which stone is closest to the centre when scoring. There is also a "hack" at the end of the sheet which players push against when sliding a stone.