| 摘要 |
<p>A core element preferably of plastic material is provided wherein one embodiment of the core element comprises a tubular body member and a tubular coupling member disposed within one end of the tubular body member and extending axially outwardly therefrom, and a tubular coupling member disposed within the other end of the tubular body member and also extending axially outwardly therefrom, including also diametrically opposed lug members extending radially outwardly from the tubular coupling member that engage a slot disposed in the wall of the tubular body member whereby the tubular coupling member may be moved into and out from the tubular body member as in a telescoping manner.</p> |
