Coca-Cola is giving away more than 4 million drinks this summer in Great Britain as it launches Coke Zero Sugar with a new formulation and new look. It’s part of the company’s goal to help consumers manage the added sugar in their diets.

The company spent several months and nearly $40 million to develop the new recipe, which comes closer than ever to the 130-year-old original, but without the sugar. People in the U.K. will be able to try it at events such as the LondonBarclaycard Presents British Summer Time in Hyde Park and a pop-up Coca-Cola Zero Sugar photo booth at Camden Beach Bar.

The new name, changed from Coke Zero, makes it clearer that the drink is sugar-free, while a redesigned package, with its signature red disc, aligns it with the new ‘One Brand’ look across Coca-Cola products. Zero Sugar is available in increasingly popular mini can sizes of 150 ml (5 oz) and 250 ml (8.5 oz).

“It’s the biggest investment we’ve made in a new product launch for a decade,” says Jon Woods, general manager of Coca-Cola Great Britain, which is spending $13 million on the marketing campaign.

Coke is also actively working to increase the share of low- or no-sugar drinks it sells. In Great Britain, that share is currently 45 percent; the goal is 50 percent by 2020. Within the food and drink category, only soft drinks have seen a decline in sugar purchased—13.6 percent over the past five years.

The sugar cuts aren’t just happening within the Coca-Cola brand. Coca-Cola Great Britain has also reduced sugar by at least 30 percent per drink in brands including Fanta, Sprite, Dr Pepper, Oasis, Lilt and Schweppes Lemonade. That removed 16,000 tons of sugar from the British diet between 2013 and 2015.

Yet the changes require more than just dialing down sugar content. “The first step is about going further than just making a no sugar drink that tastes great,” says Woods of the Zero Sugar reformulation.

“It’s about creating a drink that tastes great and replicates the taste and feeling you get from a drink that has sugar,” he says. “That’s not an easy task and it’s tricky to mimic. It takes time and testing. We've focused on that with this new recipe.”