Python - Error de instalación CV2

ERROR: Could not find a version that satisfies the requirement opencv_python-3.4.6-cp36-cp36m-win_amd64 (from versions: none)

ERROR: No matching distribution found for opencv_python-3.4.6-cp36-cp36m-win_amd64

Al tratar de instalar mediante el comando (pip install cv2) en Windows me dice ese error y no me deja instalar cv2
He instalado (pip install opencv-python) pero no me reconoce los comandos de cv2