At the Drive-In is an American post-hardcore band from El Paso, Texas, formed in 1994. The band currently consists of Cedric Bixler (vocals), Omar Rodriguez (guitar, vocals), Paul Hinojos (bass), Tony Hajjar (drums) and Keeley Davis (guitar, vocals). After several early line-up changes, the band solidified into a five-piece, consisting of Bixler, Rodriguez, Jim Ward, Hinojos and Hajjar. At the Drive-In released three studio albums and five EPs before breaking up in 2001.

At the Drive-In's style is usually described as post-hardcore. Their sound has also been called punk rock, emo and art punk. Some of the group's influences are Indian Summer, Swing Kids, Fugazi, Sunny Day Real Estate (referred to by Ward as "Fugazi beyond Fugazi"), Bad Brains, and the Gravity Records-led post-hardcore sound of the 1990s that featured acts such as Antioch Arrow and Heroin. In their last period before their initial breakup, the biggest influences of At the Drive-In included bands such as Drive Like Jehu and The Nation of Ulysses, with frontman Bixler-Zavala going on to say that "there would be no Relationship of Command without Drive Like Jehu." The band also performed cover versions of songs such as "This Night Has Opened My Eyes" by The Smiths and "Take Up Thy Stethoscope and Walk" by Pink Floyd, both included in the 2004 compilation This Station Is Non-Operational. Their name was taken from the fact that Bad Brains took their name from the Ramones' song "Bad Brain" (from Road to Ruin), and Bixler liked the Bad Brains' song title "At the Movies" (track featured in Rock for Light); while Ward liked "at the drive-in", and his suggestion would eventually win out.  Though In/Casino/Out was recorded live, "Relationship of Command may very well be the first record to harness the chaotic balance of adrenaline and intellect of ATDI's live performance." "Ross was instrumental in bringing out a lot of feeling from us," Bixler recalls. "We channeled a lot of emotion into this record. He pushed us farther than we thought we could go. I learned to cut loose the way we do live and not to be afraid to break something or whatever." While capturing the essence of ATDI's live shows in a way never before seen, the record also featured some of the band's most experimental songs, including "Rolodex Propaganda," "Non-Zero Possibility," and "Invalid Litter Dept."  The band's guitar-playing, in the majority of their songs, is characterized by unusual chords, a fast tempo, and a quiet-loud-quiet song structure. While Jim and Paul provided the rhythmic structure of the song, Omar often played more experimental riffs and melodies over the top. Effects were heavily used by Omar, especially on Relationship of Command, while Jim used the keyboard to create melody, often switching between the guitar and keyboard such as in "Invalid Litter Department." Answer this question using a quote from the following article:

What type of instrument they use to play post-hardcore ?
Jim used the keyboard to create melody, often switching between the guitar and keyboard such as in "Invalid Litter Department."