Somfy motorised systems are compatible with most external Venetian blinds. What type of external Venetian blinds do you have? - Standard external Venetian blinds: The adjustable slats are connected by visible cords passing through slots in each slat. - Metal external Venetian blinds: These types of external Venetian blinds have slat adjustment and drive mechanisms concealed in the channels. The blind slats can also come in different shapes - flat, Z-shaped, or curved depending on the design, strength and desired effect.