| 摘要 |
A sprue dowel has a radially projecting embeddable portion ( 12 ) and an attachment portion ( 21 ) formed as a hollow cylindrical shaft ( 24 ) provided with a plurality of spaced from each other, furrowed retaining projections ( 26, 27 ) formed on an outer circumference of the shaft and extending parallel to a longitudinal axis ( 25 ) of the sprue dowel ( 11 ).
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