It really looks very similar to a hose clamp, and what a hose clamp is is a band that's got notches so that as you turn a screw on the band, it decreases the circumference of the band itself.

它看起来真的很像软管夹，软管夹是一个有缺口的带子，所以当你转动带子上的螺丝时，它会减小带子本身的周长。