the lp was soon confronted by the "45", a diameter fine-grooved vinyl record playing at 45 rpm. it was introduced by rca victor in 1949. to compete with the lp, boxed albums of 45s were issued, along with ep (extended play) 45s, which squeezed two or even three selections onto each side. despite these efforts, the 45 succeeded only in replacing the 78 as the format for singles.