OLD-SCHOOL deejay Mad Cobra’s gold-selling single, Flex, has been sampled by American girl group Fifth Harmony on their latest single All in My Head (Flex).

The song, second from the quintet’s sophomore album 7/27 (Syco/ Epic Records), is due for release tomorrow. Clifton ‘Specialist’ Dillon, who co-produced Flex with Sly Dunbar, said he gave the group the nod.

“I gave the clearance for the sample to be used and all the necessary paperwork was done,” Dillon told the Jamaica Observer yesterday.

Recorded at producer Donovan Germain’s Penthouse studio in Kingston in 1992, Flex was featured on Mad Cobra’s Hard to Wet, Easy to Dry (Columbia Records).

It was certified gold by the Recording Industry Association of America (RIAA) and reached number one on Billboard’s Rap Singles Chart — a first for any Jamaican artiste.

Fifth Harmony — comprising Ally Brooke, Normani Kordei, Dinah Jane, Camila Cabello, and Lauren Jauregui —- appeared on the second season of X Factor USA in July 2012.

The group signed a joint deal with Syco Music owned by Simon Cowell, and Epic Records, LA Reid’s record label, after finishing in third place on the show.

So far, the group has sold more than eight million records. The group’s current single, Work From Home, included on 7/27, peaked at number five on the Billboard Hot 100 Chart two weeks ago.