Looks like a discontinued router on clearance.
From MSY's fb page:
3 Day SALE (From 17-19/05/2013)
WD Mynet N600 HD Dual-Band Wireless Router
$19 (Was $69)
Pre-order in-store starts now
*Due to high demand, ONLINE DELIVERY is only available from 17-19/05/2013
The My Net N600 HD Dual-Band Router creates a wireless network that accelerates video, gaming and chat with FasTrack technology, delivering fast HD streaming with combined wireless speeds up to 600 Mbps. It features simple setup, four fast Ethernet ports, and one USB port for printer sharing.
Exclusive FasTrack Technology instantly detects entertainment traffic and automatically prioritizes bandwidth for entertainment applications. With FasTrack technology you can stream accelerated, smooth HD entertainment to your smart TV, tablet, smartphone, computers and other Wi-Fi connected devices.
My Net N600 can also be customized so FasTrack instantly recognizes and accelerates your favorite entertainment and comes tuned to prioritize Netflix, CinemaNow and YouTube instantly.
Up to 300 + 300 Mbps wireless speeds - with combined dual-band speeds up to 600Mbps on the 2.4 and 5 GHz bands, the My Net N600 delivers fast Wi-Fi speeds for your entertainment.
Simultaneous dual band - double your bandwidth with 2.4 and 5 GHz bands working simultaneously to increase throughput and reduce interference.
An unboxing if you want to see what's included in the box: http://www.youtube.com/watch?v=clzo-FJM6wg
Doesn't look like its DD-WRT compatible.
Product page: http://www.wdc.com/en/products/products.aspx?id=730