Horizontal (H) and Vertical (V) channels do not require them. The small shape of the adapter ensures the back panel of an Extron Matrix looks neat even when many Video DC Blocks are attached. The Video DC Block isolates the DC offset from a video source to an Extron product, preventing video distortion. Twist Video DC Blocks onto the RGB inputs of Extron products, then twist cable onto the Video DC Blocks. Horizontal (H) and Vertical (V) channels do not require them. The small shape of the adapt