Biography: Kelvin Mercer (born August 17, 1969), also known by his stage name Posdnuos, Plug 1 and occasionally Pos, is an American rapper and record producer best known for his work as one third of the hip hop trio De La Soul. Through his work with the group, Mercer is considered to be one of the most consistent and underrated MCs of all time. Beginning with the highly acclaimed 3 Feet High and Rising in 1989, Mercer has gone on to release nine albums with De La Soul.