Boston has always been on the cutting edge of underground Hip Hop music. From trailblazing artists like Edo G and the late Guru to more contemporary names like Statik Selektah and Slaine, Beantown has kept its finger firmly in place on the pulse of the underground.

Despite these artists’ significant contributions to the Hip Hop game, perhaps one of Boston’s most heralded underground Hip Hop groups is 7L & Esoteric. Since their 2001 debut The Soul Purpose, the duo have left ears ringing with their combination of hard-hitting beats and super-lyrical rhymes. Now, after four years of solo and side projects, 7L and Es reunite with perhaps one of their most sonically diverse and lyrically driven efforts to date, 1212.

From the beginning of the album’s epic opening track “Retrospects,” it’s clear that 7LES mean business. Es jauntily flows over 7L’s thunderous kicks and snares and unflinching guitars with a veteran finesse, filling in newcomers about the duo’s storied history in the game. And of course, Esoteric is back in business when it comes to talking shit and throwing lyrical haymakers. Songs like “No Shots” find the emcee at his shit-talking best as he takes aim at perceived newbie’s like Drake and Wiz Khalifa.

At the same time however, perhaps Esoteric’s finest lyrical moment come on the more concept-oriented tracks. On the song “The Handle,” he spits with rapid-fire precision alongside the legendary Sadat X, as the two lyricists go into ESPN Classic mode and reminisce about their favorite basketball players. Similarly, “I Hate Flying” is a slyly ironic and yet surprisingly nerve-racking trip. His attention to detail in both songs is a testament to his vast ability as an emcee and growth as an artist since 2006’s A New Dope.

While 7LES more than hold it down on solo tracks like “New Rapper,” “Zoo” and “Aneurysm,” the collaborations featured on 1212 are truly something to behold. The Boston duo enlisted a bevy of fellow underground luminaries for some head- knocking, boom-bap action. The epic “Bare Knuckle Boxing” harkens back to 7L and Es’s debut album as Es, Ill Bill and Army of the Pharoahs fam Vinnie Paz and Reef The Lost Cauze lay out a lyrical beat-down over one of the album’s grimiest beats. Similarly, Es and Demigodz/AOTP alum Celph Titled tear mics apart over a funky bass-heavy beat on “Run This.” 7LES even succeed when they extend themselves beyond their own camps, verbally sparring with the left coast’s Evidence and the Alchemist on “Drawbar 1-2” . Yet perhaps the album’s best collaboration is “12th Chamber” with the Wu-Tang Clan’s Inspectah Deck. Linking up for the first time since “Speaking Real Words,” the two emcees sound triumphant rocking over a fantastic violin sample.

1212 isn’t exactly perfect, however. A few songs, including “For My Enemies,” fail to do the rest of the album’s numerous moments of brilliance the proper justice. Similarly, some of the album’s production is not quite up to par given 7L & Esoteric’s illustrious track record. Despite the incredible drum programming, 7L & Esoteric’s joint beat for “No Shots” features a hackneyed groove that sounds more like an Ed Wood movie than a Hardcore Rap record. Similarly, for a song that features super-producers the Alchemist and Evidence, Esoteric and DC the Midi Alien’s “Drawbar 1-2” is overly simple and devoid of tension. Yet a few less-than-perfect beats barely leave a scratch on 1212, as the duo kicks it into high gear on tracks like the menacing “Zoo” and subtle “The Handle.”

After a six year absence that left fans questioning the duo’s future, 7L & Esoteric do not disappoint on 1212. Both parties sound more focused and able to stylistically branch out into new musical territories. Let’s just hope we don’t need to wait another half a decade for a new release from two of Beantown’s best.