| 摘要 |
<p>It includes a tubular body made of non-magnetic material (1), a seat (2) carried by the tubular body, a closure member (6) located inside the tubular body facing the seat (2) and including a shutter (7) connected to an operating ring (8) made of magnetic material extending substantially coaxially to the tubular body (1) facing a magnetic-field generator (12) located outside the tubular body and associated with an operating member (13). <IMAGE></p> |
