Two high quality steel plates with measuring scales of unknown purpose in a fitted wooden box.
The box has space for six plates but only two are present. It appears from the indentations in the foam in the lid that no more than two have ever been present in the box.
One of the plates is marked “10883” and “20KN”. The other is marked “58140” and “2-TON”.
The plates may have been used for impact testing.