Cadbury is emulating arch-rival Mars by extending its Boost and Double Decker bars into Duo formats in a move it says will achieve what its rival has failed to - revive sales of larger bars.

Mars, which has Duo formats for Mars, Milky Way, Bounty and Snickers, currently leads the share-size market, but the sector recently recorded a sales decline of 7.4% year-on-year [Nielsen Scantrack w/e 7 February].

The new 85g Cadbury Duos, which are split into two sections to allow consumers to save or share the chocolate, would reignite interest, predicted Cadbury trade communications manager Kate Harding.

"There has been a lack of innovation in the larger bar category, which has given us an opportunity to bring interest back by offering a greater variety to impulse consumers," she said.

As well as launching the new Duo bars, Cadbury has overhauled the design of regular-sized Boost and Double Decker bars.

"Boost has been brightened with a new sky blue wrapper, whilst the colours of Double Decker have been made more vibrant and the logo size increased," said Harding.

"We are confident that this will create greater stand-out on shelf, enabling consumers to find them more easily.

"The change of packaging and the launch of Duo broadens the appeal of these two Cadbury singles even further."

The company has also renamed its Dairy Milk 8 Chunk bar as Dairy Milk Bar and a Half, in a bid to boost the bar's appeal with women. It will be available in Dairy Milk, Whole Nut and Fruit & Nut flavours.

All the new products will be supported by a £1.3m campaign including TV sponsorship and PoS material.

Duo Boost and Double Decker and Bar and a Half will be available in store from 18 May. The regular 60g Double Decker and 60.5g Boost will cost 46p and 48p respectively, both 80g Duos will cost 65p and the 75g Dairy Milk Bar and a Half will cost 69p.

This is the latest in a raft of new product development activity from Cadbury, which rolled out a Bitesize range earlier this month.