Thousands of UK workers are starting a four-day workweek from Monday with no cut to their pay in the largest trial of its kind.

The pilot program, which will last for six months, involves 3,300 workers spanning 70 companies, ranging from providers of financial services to a fish-and-chip restaurant.

During the program, workers receive 100% of their pay for working only 80% of their usual week, in exchange for promising to maintain 100% of their productivity.

The program is being run by the nonprofit 4 Day Week Global, Autonomy, a think tank, and the 4 Day Week UK Campaign in partnership with researchers from Cambridge University, Oxford University and Boston College.

Sienna O'Rourke, brand manager at Pressure Drop Brewing, an independent brewery in London, told CNN Business that the company's biggest goal was to improve the mental health and well-being of its employees.

"The pandemic [has] made us think a great deal about work and how people organize their lives," she said. "We're doing this to improve the lives of our staff and be part of a progressive change in the world."