If you have one of these, you can sell it for half a million bucks. What is it?

Cracked by: Sumanth Patlolla, Amarendra Kumar, raklodramA, Manish Achuth, KK, Jayaprakash B R, Bharath, Supritha Maiya, Ananth, Don42, Rogi, sandeep bhat, rohanquizzer, Bipin Banavalikar, rickde and Anand