This component is a Heavy duty version of the the standard TRA31H it designed  for use on a single track to enable the cording to be kept compact within the track plan. It comprises a flat plate carrying two 90mm diameter black plastic ball raced capstan pulleys mounted side by side, each in their own metal bodies. On the centre line there are two 13mm holes  to provide for fixing the fitting to the track with M12 nuts and bolts. The metalwork is finished  black.

TRA0902 formerly TRA31HHD