New, unused, and working perfectly. This active adapter converts a DisplayPort output from your computer into a Dual Link DVI-D signal that will run a DVI-D monitor up to 2560x1600 resolution. This is not a simple passive adapter that will only drive single-link DVI-D monitors to 1920x1200, this one works with big monitors like the Dell 3007WFP-HC.  Power is supplied through a USB connector on the second cable (see pictures).

You must of course use a dual-link DVI cable to drive a dual-link DVI monitor (not included; most DVI cables are single link so watch out for this).