A strap has an extension element and a support element. The lock piston has a wedge surface at an end thereof. The world server is responsible for the overall administration of the virtual reality world including the area servers. The type of layer is selected from an ETL, an HTL, an HIL, a spacer and a capping layer. A fibrous material is selected having a low-pass transfer function and low acoustic loss in its low-frequency pass band. For attaching the object, the button extends through the object hole with the abutment wall adjacent the object and the abutment surface adjacent the channeled member.