In its preferred embodiment, a pair of shoulders are formed on the sides of a circular disk like head portion and a pair of spaced apart surfaces are formed on the socket portion which contact the shoulders of {HEAD ~ the head portion} when {TAIL ~ the phalangeal component} is at maximum flexion 
In its preferred embodiment , a pair of shoulders are formed on the sides of a circular disk like head portion and a pair of spaced apart surfaces are formed on the socket portion which contact the shoulders of { HEAD ~ the head portion } when { TAIL ~ the phalangeal component } is at maximum flexion
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