This is a set of stainless adjuster plates that connect the shroud to the chainplate.  One is flat and one is hooked.  The hooked one acts as a guy hook when flying the spinnaker.  These used to be standard on racing Flying Scots prior to the guy hooks being installed directly on the deck.  The current standard rigging for the racing Flying Scots utilizes the guy hooks on the deck and the 6 hole fine adjuster plates for the shrouds.  These adjuster plates are linked to below.