The Mark 17 (XVII) or otherwise known as the "Heartbreaker", is an Artillery Level RT Suit and was one of the many newly built suits created by Tony Stark, sometime after the events of The Avengers.
It was featured in the movie Iron Man 3, and made its debut in the movie, when Tony ordered J.A.R.V.I.S. to initiate the "House Party Protocol", in which it was activated along with all the other suits to aid Tony in his battle against Aldrich Killian.
The suit earned it's name the "Heartbreaker", because it has an oversized chest RT, which can fire powerful blasts. The Mark 17 can fire narrow or wide beams and can also generate a Repulsor Shield for protection.