mansionz is an American alternative hip-hop duo composed of American singer-songwriter Mike Posner and American hip-hop recording artist, producer, and singer Matthew Musto, better known by his stage name Blackbear. They released their debut studio album, Mansionz, on March 24, 2017. Mansionz was formed when longtime collaborators Matthew Musto (otherwise known as Blackbear) and Mike Posner formally came together and formed an R&B-rap duo. Previously known for his hit singles "Cooler Than Me" and "I Took A Pill In Ibiza," Posner was first featured on a Blackbear track in 2012, when Blackbear's debut mixtape Sex was released. At that time, the two musicians were already good friends and had worked together in the past on Justin Bieber's 2012 single "Boyfriend". Prior to the official debut of Mansionz, Posner and Blackbear had worked together on several tracks including "Boyfriend," "Anyone But Me," Marauder Music," and "OshFest". By December 9, 2016, Posner and Musto had released their debut single under the name Mansionz, titled "Stfu".