Melting point of pyrex glass is about 800C. Regular glass in eg. drinking glasses is about 1500C. There are a few types of glass with what is considered low melting points, about 500C, that are used in residential windows. Nonetheless, those temperatures can not be reached in a household microwave. A glass can shatter in the microwave due to material fatigue but it will not melt. Hence, regardless of how it is labelled and sold, the pitcher on the photo is not glass.