Another week, another pretty great mixtape of horny, spacey California R&B. And why not? The stuff sounds great in summertime, existing specifically to soundtrack sunlit top-down cruises and sweaty-nightclub seduction attempts. Last week, it was Ty Dolla $ign’s uproarious Beach House 2, an act of ribald assholism so bald and confident that it felt almost avant-garde, Ty’s dehumanizing robotic come-ons airily lacing his own exquisite studio-pop production. Fellow L.A. crooner TeeFLii (pronounced “t-fly,” god knows why he spells it that way) isn’t the transformative figure that Ty is. In plenty of ways, he’s a pretty normal radio-R&B guy, blessed with a thin but buttery tenor that slides right through tracks with a pleasantly anonymous grace. In a lot of ways, he’s like Trey Songz, without the battalion of crack songwriters that Trey Songz has at his disposal. But TeeFLii matters, mostly because of the guy he shares mixtape billing with. At this point, in the summer of 2013, everything DJ Mustard touches demands to be heard.

If you’ve been steadily reading this column, or listening to rap radio over the past year or so, you know DJ Mustard, he of the deftly placed handclaps and eerily memorable two-finger keyboard riffs and vast expanses of empty space. Maybe more than any producer since Dr. Dre left rap to become a headphones baron, Mustard has been responsible for giving West Coast rap a sonic identity that it badly needed, and his sinister and spacious tracks are that much more impressive for sounding nothing like the California stuff that came behind him. (Echoes of hyphy and jerk run all through Mustard’s catalog, but the weirdly prim and dinky minimalism is a relatively new phenomenon, nothing that any other producer pulls of with anything like Mustard’s panache.) Mustard’s Ketchup compilation one of the handful of 2013 mixtapes that you really, really need to hear. And now Mustard is back, producing every track on TeeFLii’s Fireworks (which, you see, came out on the 4th), a fact that makes Fireworks a must-download.

Now, to be clear: TeeFLii isn’t the Aaliyah or the Ginuwine to Mustard’s Timbaland. If anything, he’s the Nicole or the Tweet. (If Mustard has a Missy, it’s the solidly pedestrian Compton rapper YG, a pretty clear sign that Mustard should get himself some more-interesting regular collaborators.) But Nicole and Tweet, despite not being that interesting on their own, made some truly great music when they were within Timbaland’s web, and TeeFLii has made some pretty great music here. When Mustard’s working with TeeFLii, he dips a bit away from his usual minimalism, letting in some of the studio-pop flourishes that Ty Dolla $ign uses so well on his own. And the ’80s-style gleaming blooz-rock guitars on “Better Know,” or the butt-rock guitar solo that suddenly erupts on “They Know,” work scarily well with Mustard’s backfist bass-hits and his itchy hi-hats. And when Mustard’s sci-fi keyboards are hitting with their usual alchemical immediacy, TeeFLii understandably sounds a little more confident. Check the little hiccups he adds to the end of his phrases on “So Good”; you don’t sing like that unless you’re feeling really good about yourself.

Much of Fireworks concerns sex, of course, and TeeFLii is very much the type of singer to sing an entire song about fucking on the floor and then call it “Fuckin On The Floor.” But compared to a contemporary like Ty Dolla $ign, who shows up on the Fireworks track “Sex Sounds” (which is about making sex sounds), he’s positively chivalrous. As a singer, TeeFLii’s single most endearing quality is this: He projects a certain lovable, vaguely embarrassed tentativeness, like a middle schooler going in for his first kiss. My favorite line: “Let me get a [slight pause] private dance / Can you do it with [slight pause] no pants?” But really, the best reason to listen to Fireworks is to get another hour or so of Mustard beats, to hear the way they slowly build themselves up from the intro until his “Mustardonthebeat ho” drop comes in (at the exact perfect moment every time), the way they bend the space around them. He is having a magical moment right now with a production style that could, in the long run, turn out to be a brief and limited thing. Ask Lex Luger: Those moments are short, but they’re glorious, and you need to enjoy them when they’re happening, before they disappear from the air completely. Like fireworks.

Download Fireworks here.