A metal coupling device consisting of an oblong piece internally threaded at both ends into which the two sections of a threaded rod are screwed in order to adjust the tension of the rod.

• 花篮螺丝，松螺旋扣一种金属的连接环呈椭圆形，两端有内旋螺纹，用来拧紧带螺纹的拉杆的两个部分从而调整拉杆的张力