The Jung 21420 1S R is a compact 1 TE KNX spatial/line coupler (MPN 214201SR, EAN 4011377322073). It provides galvanic isolation between two KNX lines and supports configuration as a spatial coupler, line coupler, segment coupler (up to 4 segments), or line amplifier. It is compatible with KNX Data Secure and Secure Proxy, supports filter tables, a manual service button, and ETS update via the ETS Service app. Typical dimensions ~92 x 75 x 24 mm, weight ~90 g, power supply 21–32 V DC (upper line).