최규열 – 거북이
Track 01 from Single '거북이'
훈재정, 최규열 – 구라 (GURA)
Track 01 from Single "구라 (GURA)"
Release Date: 2017.04.05
최규열 – FOOL
Track 01 from Single "FOOL"
Release Date: 2021.09.29
훈재정, 최규열 – 도돌이표
Track 01 from Single "도돌이표"
Release Date: 2018.08.28
최규열, 정재훈 – 해
Track 01 from Single "해"
Release Date: 2019.01.12