Son by Four is a Latin music group from Puerto Rico, well known for their English U.S. pop hit "The Purest of Pain (A Puro Dolor)". The group is now independent, as they founded their own label SB4 Music Group in 2003.

Son by Four was created by Panamanian producer and songwriter Omar Alfanno and their members Ángel López, Pedro Quiles, and brothers Javier Montes and Jorge Montes. Currently, the band is formed by the Montes brothers, Javi and Jorge.

Source: Wikipedia (https://en.wikipedia.org/wiki/Son_by_Four)