Myriad UI Kit (Free Download)

Download it at http://designcurate.com/resource/myriad-ui-kit

"This awesome UI kit contains various elements: buttons, sliders, input fields, notifications, and other form elements."

The MyriadUI set uses "Myriad Pro" — regular and semibold — for all of the elements. All the elements and type are set according to a 24px baseline, subdivided in 6px units.