Producers looking for melodies, chords, and chord progressions will love loop packs. They're also useful when you require background music that isn't too loud or distracting from the vocals.
A loop pack is an audio package that contains synth and drum beat loops at various tempos to offer composers an idea of how these sounds would fit with diverse styles of music. Most loop packs begin with an intro or melody, which is usually accompanied by slow-to-medium tempo percussion. If you're writing vocal tracks and finding it difficult to come up with catchy melodies on your own, these melodic loops can come in handy.