| 摘要 |
<p>The element comprises a base (1) with lugs (2 and 10) provided with extensions (4 and 17) respectively, the latter having slots (5-14) and tongues (7 and 16) engaging with corresponding shoulders (21, 22) of the lugs (2 and 10), the extensions being locked by means of the tongues (9 and 13). <IMAGE></p> |
