OS X 10.11 El Capitan was released on September 30, 2015 after being announced on June 8, 2015. Similar to Mac OS X 10.6 Snow Leopard, Apple described this release as containing "refinements to the Mac experience" and "improvements to system performance" rather than new features. Refinements include public transport built into the Maps application, GUI improvements to the Notes application, adopting San Francisco as the system font for clearer legibility, and the introduction of System Integrity Protection. The Metal API, first introduced in iOS 8, was also included in this operating system for "all Macs since 2012".