Synk: Parallel Line contains four tracks. The first track, "Up", performed by
Karina, was described as a
hip-hop dance track with a catchy chorus and minimalist beat. Written solely by Karina, the lyrics project confidence and pride, aiming to captivate listeners. The second track, "Dopamine", which performed by
Giselle, was described as an
R&B song that contains the complex and vague emotions of pretending not to be in love in order to hide one's true feelings for the other person. Giselle also participated in writing and composing the song. The third track, "Bored!", performed by
Ningning, was described as an R&B dance song featuring a unique top line and
rhythmic track. The lyrics, in which Ningning participated in writing, contain the dual emotions of love that starts off strong and intense but ends up becoming boring. The last track, "Spark", performed by
Winter, was described as a captivating song featuring a cool
EDM sound that evokes a dreamy yet hazy atmosphere. The lyrics metaphorically express the feelings of falling in love through the imagery of a small spark. She also participated in writing and composing the song. ==Track listing==