This is a replacement part for the original shield centerpiece of the YMS-15 Gyan Master Grade model kit.
While the original part was smooth and it was intended to have a decal of the Zeon emblem applied, this model has the emblem embossed on the shield at a larger size than what is provided with the model kit.
Dimensions were taken from the original part in order to create a snap fit but some clean up and sanding may be needed for the part to fit.