Copied from a good quality Georgian cranked table fork with boxes. The boxes, tensioned with springs , are designed to be inset in the underside of the table. To buy the fork only, the reduction in price is shown below.
Centre of Prong to Centre of Prong: 3 1/16″ (77mm)
Thickness of Prong: 3/16″ (4mm)
Note: Main image is view from underside of clip – boxes are inset.