Kramer Electronics VS-21DVI VS-21DVI is a high performance switcher for DVID video signals. It switches either of 2 signals to a single output. Use Kramer Dual Link DVI cables for best results. Max Data Rate - 3 Gbps. Dual Link. DVI Input/Output - DVI-D signal (on a DVI-I connector). Compact DigiTOOLS - 3 units can be rack mounted side-by-side in a 1U rack space with the optional RK-3T rack.