OO是一把直尺，其中一端带有两个圆盘，既可以进行线性测量，也可以测量非线性的表面，它长达100厘米，包含一个齿轮和两个带标记的滚动圆盘，OO可以在物体表面滚动，根据圆盘的滚动程度，通过小窗口得到测量数据。下滚轴是毫米单位，上滚轴是厘米单位，每经过100厘米或1米将会重置。

     Titled the OO for the two circular discs at one end of the ruler, piece of stationery is capable of measuring linear as well as non-linear surfaces, up to 100 centimetres. Using a clever gear system and two marked rolling-discs, the OO ruler can be rolled on surfaces, with a set of windows depicting the measurement based on how much the discs roll. The lower roller covers the millimetres, while the upper takes care of the centimetres, resetting every 100 centimetres, or one meter.