end portion of the body portion 812 and has a screw thread formed on the surface of the first fixing portion 814 and a second fixing portion 816 which is formed at a second end portion of the body portion 812 and has a screw thread formed on the surface of the second fixing portion 816 the bail 830 includes first and second ring portions 832 and 834 having a round ring shape a first connecting portion 836 which is bent and extended in a diameter direction from the side of the first ring portion 832 a second connecting portion 838 which is bent and extended in a diameter direction from the side of the second ring portion 834 and a pressing portion 840 which connects the first and second connecting portions 836 and 838 has folds on one end and has a rectangular block shape the pressing portion 840 is connected to the first and second connecting portions 836 and 838 so that the folds are located on the top position movement of the bail 430 is limited by the first fixing member 850 which can be screwed to the first fixing portion 814 of the main body 810 and the second fixing member 855 which.