In addition to the standard for-profit and limited-liability model of the traditional corporation, other variants exist. A public-benefit corporation is state-chartered and designed  to perform some public benefit, such as the MBTA and Massachusetts Turnpike Authority. A B Corporation is a corporation certified by the non-profit B Lab for having met its standards of sustainable business practices, including high levels of public accountability, social and environmental performance, and transparency. Well-known examples of B Corporations include Ben & Jerry’s Ice Cream and the apparel company Patagonia. The B Corporation certification is similar to LEED (Leadership in Energy and Environmental Design) certification for buildings or the Fair Trade label for products such as coffee.