7 Inch Small used for Office desk height ( gives a range of 440 - 520 mm )
9 Inch Medium used for Production bench height ( gives a range of 460 - 580 mm )
11 Inch Large used for Production bench height ( gives a range of 520 - 700 mm )
14 Inch Extra Large used for Architect bench height ( gives a range of 620 - 860 mm )