The Hornby 00 Gauge Model Train Accessories R7200 Articulated Coupler X4 are ready-to-go pre-built accessories designed for Hornby trains in OO gauge. These black couplers are compatible with Hornby products, operate on DC power, and are suitable for analogue control systems. With a scale of 1:76, these couplers are perfect for enhancing the realism and functionality of your model railway layout.