None are in new production(*). 2TB is the current max for 2.5" constant use A/V drives. And that is due to the reality that the majority of the buyers of those types of drives are surveillance systems where 2TB is considered the sweet spot for capacity and thermals and pricing, so that is what the HD manufacturers design/build. (*) And TiVo is going to want to choose drives they can get new/replacement ones of. That is perhaps why the 3TB Bolt left the building earlier than others.