| 主权项 |
1. An apparatus comprising:
an outer sleeve having a first channel with an inner wall with a first number of substantially planar surfaces, the outer sleeve further having a first cylindrical lip on a first end of the outer sleeve, the first cylindrical lip having a first outer diameter greater than a second outer diameter of the outer sleeve; and an inner sleeve having a second channel and an outer wall with a second number of substantially planar surfaces, wherein the outer wall is configured to be received within the first channel, and at least one of the second number of substantially planar surfaces on the outer wall of the inner sleeve is configured to slide against at least one of the first number of substantially planar surfaces, the inner sleeve further having a second cylindrical lip on a second end of the inner sleeve opposite the first cylindrical lip, the second cylindrical lip having a third outer diameter greater than a fourth outer diameter of the inner sleeve but less than the second outer diameter of the outer sleeve, the second cylindrical lip disposed on an outer surface of a third end of the outer sleeve that is opposite the first end. |
