Compounds of formula :wherein B, X, R3, L0, L1, L2, R2, R1 and RC are defined herein. The improved polishing pad provides both the benefit of a fixed abrasive and the benefits of slurry based polishing systems. For short installation times of the footboard on the foundation, the fastening apparatus is additionally provided with a third fastening element constructed as a rigid back-reaching element, and the upper fastening element is constructed as a slide blocking element that blocks a relative displacement between the footboard and the mounting surface. An actuator is able to deform the rod such that the panel moves away from the terminal opening of the duct, thereby opening the vent. The valve assembly includes a sensor for detecting the position of the valve member to determine whether the handle is in an OFF position andor an ON position. The shape memory insulators provide insulation as well as improving comfort andor control over the engagement and use of objects, while decreasing arm and hand wear andor strain of those using the objects.