It's what?

      A chain, as in a measuring chain for measuring out a chain.
      Get the links laid correctly and in a straight line and you can measure out your own cricket pitch, now that's what I call useful.
      This one was bought at a farm sale for £2.00, a little bit of a bargain really, the whole twenty two yards you might say. It was probably, no, it was inevitably made by the local blacksmith so perhaps we should roll the whole thing out and check his calibrations.
      Cricket pitch anyone?