| 摘要 |
A tubular main bar, internally threaded, with buttress teeth, from each end, with a stop in the middle, and an inner bar inserted in each end, having a single tooth element, spring pressed radially outwardly, forming a buttress tooth engaging the buttress teeth in the main bar. The inner bars can be pushed inwardly, but must be threaded, or turned, out. The weights are fitted on the inner bar at each end, against the end of the main bar and a locking collar interlocks with the outer end of each inner bar, and holds the weights. The outer surface of the locking collar and of the inner bar lie in a common plane, defining the end of the dumbbell. The inner bars cannot be threaded completely out of the main bar, except by special manipulation of the tooth element in the inner bar, through an inconsipicuous opening.
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