Lotus, 311, Chris Robinson Brotherhood, and Electric Hot Tuna will join Colbie Caillat and Christina Perri as headliners for this year’s Great South Bay Music Festival.

Long Island’s biggest music festival has expanded to four days this year at Shorefront Park in Patchogue, from July 16-19.

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Tickets for opening night featuring Caillat and Perri are already on sale. Tickets for the other days go on sale at 10 p.m. Friday through greatsouthbaymusicfestival.ccom. Pre-sale tickets go on sale at 10 a.m. Wednesday through the site.

As in the past, Friday will focus on rock, with 311 and Mighty, Mighty Bosstones headlining. Saturday will remain roots rock and jam bands day, with Sister Sparrow & The Dirty Birds, joining Lotus and Chris Robinson Brotherhood.

Sunday will once again be classic rock day. Along with Electric Hot Tuna, Jefferson Starship with Paul Kantner, New Riders of the Purple Sage and Zen Tricksters, Foreigner’s original singer Lou Gramm will be on the 17-artist bill. The Laurie Berkner Band will play a separate children's show on Sunday before the festival grounds open.

Festival promoter Jim Faith says that this year’s lineup is the event’s most diverse yet, adding that the main commitment is to “just lay great new music on everyone.”