A tile is provided for covering surfaces in the form of one or more metallic plates. The apparatus includes a rod; a clamp that includes multiple arms and attached to a one end of the rod; a sleeve coupled to the rod and adapted to enclose the clamp, where the arms of the clamp are pushed towards each other to engage with a pin in the enclosed position. Items of user information, request-associated information, andor ad information can be weighted based on previous uses of such information in the serving of ads and the performance of those served ads. In a double gate structure, an oxide is used on the upper surface between the source and drain electrodes and an additional metal layer is used on top of this oxide to act as a second gate electrode. The invention further relates to a pair of spectacles comprising a spectacle lens device, to the use of the inventive spectacle lens device and also to a method for operating an electrically adaptive area. The solid acid catalyst is prepared by treating a strong acid cation exchange resin with aromatic sulfonic acids in a solution.