It depends on whether you're in a Motorola or a SA/Cisco system/area.
The Xfinity X1 (»[X1] Xfinity TV on X1 Platform and X1 Remote Control App!
) is the latest, but has limited availability right now.
For Motorola systems, the latest DVR models are the DCX3400 and DCX3501 (aka the Motorola RNG200N): »Motorola DCX-3400 vs. DCX-3501?
For SA/Cisco systems, the latest DVR models are the Cisco RNG200 and RNG200N (AnyRoom).
You can see these models and get a copy of their user manuals here: »customer.comcast.com/help-and-su ··· manuals/
There was also this recent thread: »[DVR] Latest Comcast DVR