Is this pad good for the knee? I see this is less expensive than the one made for the knee. Is this just as good?

Thermotex Gold 遠赤外線電熱パッド。生理的けいれん緩和、腰痛、関節炎の痛み緩和のための加熱パッド。肩の加熱パッド。坐骨神経痛の緩和装置。洗濯機洗い可能なカバー。