| 摘要 |
An apparatus comprises an object and a plurality of roller units on said object, each roller unit comprising at least one roller element and being switchable between a mobile mode in which the apparatus is moveable across a surface on which said apparatus is positioned in use by rolling on said roller elements, and an immobile mode in which movement of the apparatus across a said surface is inhibited. The roller units are configured such that manual depression of the object towards a said surface causes switching of at least one roller unit between the mobile and immobile modes. |
