Wooseok x Kuanlin

Wooseok X Kuanlin (우석X관린) was a South Korean musical duo formed by Cube Entertainment in 2019, composed of Wooseok of Pentagon and Lai Kuan-lin, a former member of Wanna One. On February 20, 2019, Cube Entertainment announced the formation of a new group project featuring Lai alongside Wooseok. The duo debuted on March 11 of the same year with 9801, featuring title song "I'm a Star".

Pre-debut
On February 19, 2019, Cube Entertainment announced a new unit. On February 22, Cube officially revealed the unit's name and members.

2019: Debut with 9801
Wooseok X Kuanlin debuted on March 11, 2019 with the EP 9801 and its title track "I'm A Star". The EP contains one unit track and two solo songs each from the members. It debuted at number two on the Gaon Weekly Album Chart and sold over thirty-six thousand copies.