For sale is a StarTech "4 port High Resolution Dual Link DVI USB KVM Switch with Audio" Part# SV431DVIUAHR. Includes only what you see pictured: rack mount "ears", power supply, manual, and some kind of rack extension brace (I never used it so not sure how that part is used).
DOES NOT INCLUDE any cables. You can get them from StarTech for whatever length you want. Other manufacturers KVM cables should work as well
From a non-smoking household.