LONDON – In the United Kingdom, McDonald’s is testing its thickest, meatiest burger yet in an attempt to outshine fast-casual rivals like Byron Hamburgers and Shake Shack, the Wall Street Journal reports. The new premium patties pack 30% more beef than regular ones, and are entirely made from Irish and British beef. Those burgers are served in black packaging and cost roughly twice as much as regular burgers.

The move mirrors one McDonald’s made earlier this year in U.S. locations with its premium sirloin burgers, which are touted as limited-time items. In England, the new burgers were available in London, Manchester and the Southeast, with an additional 400 restaurants adding the item in the summer of 2016.

The premium burger debut comes on the heels of other changes to its U.K. stores, such as testing tableside service and digital ordering kiosks. The chain also has earmarked considerable funds for revamping restaurants to improve customer experience. So far, McDonald’s has altered approximately 300 of its 1,250 U.K. units, at a rate of around 30 restaurants a month.

McDonald’s has an aggressive rate of expansion in the United Kingdom, with a goal of opening 40 new locations annually, plus 400 drive-through units by 2025. The fast-food chain has a good following in the United Kingdom, with a little more than half of residents saying they had visited McDonald’s from February to April 2014.