Schynbalds were an early experiment in plate armour

Plate armour

Plate armour is a historical type of personal armour made from iron or steel plates.While there are early predecessors such the Roman-era lorica segmentata, full plate armour developed in Europe during the Late Middle Ages, especially in the context of the Hundred Years' War, from the coat of...

 for the lower leg. Schynbalds were metal plates strapped over chausses

Chausses

Chausses are armour for the legs, usually made from mail. They could extend to the knee or cover the entire leg. Chausses were the standard type of metal leg armour during most of the European Middle Ages. Chausses offered flexible protection that was effective against slashing weapons...

. Each schynbald was a single piece of steel that covered the front and outside of the shin. Schynbalds did not enclose the lower leg: hence, they were not true greave

Greave

A greave is a piece of armour that protects the leg.-Description:...

s. Schynbalds first appeared during the late thirteenth century and remained in use during the fourteenth and fifteenth centuries.

Complete suits of armor survive only from the latter part of the schynbald era. In fifteenth century gothic armour they were strapped not to mail but to fastenings on a padded undergarment. By the early fifteenth century greaves had supplanted schynbalds in white armour. Schynbalds were essentially obsolete by the sixteenth century.