| 摘要 |
A coupling device is described and formed of a flexible tubular outer connecting element and a more rigid insert element sized to snugly fit into the bore of the connecting element. The elements are formed of vinyl material of different hardness so that their connection is accompanied with high frictional surface engagement. The resilience of the outer connecting element is selected sufficiently high to contract slightly and more tightly grip the insert in response to a separating force while facilitating connection with a slight expansion in response to a compressional connecting force applied to the elements. In one embodiment a ring fastener is formed for use as a key ring, or loose-leaf paper binder, apparel fastener and the like. Several embodiments are described.
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