No.6 Collaborations Project is a strangely utilitarian title, describing the contents lying within the confines of Ed Sheeran's fourth studio album. That's right -- fourth album. The "No.6" in No.6 Collaborations Project refers to what was originally intended to be his sixth EP, following a 2011 set that was also dedicated to collaborations. The line separating this full-length LP from the previous EPs is blurry: No.6 weighs in at 50 minutes, which is just 15 minutes longer than No.5. To complicate things further, Sheeran designates No.6 Collaborations Project as a compilation, which could be a roundabout way of lowering expectations after three blockbuster solo albums in a row. It also could be an admission that No.6 Collaborations Project plays not like an album but rather a digital play list, purportedly hopping from genre to genre but maintaining a low-key, amiable groove that can pass as pop, hip-hop, R&B, adult pop, mall music, a retro throwback -- whatever genre you'd like, really. It's a feature endemic to streaming services, where seemingly disparate artists are united by tempo and chill, but it's something of an innovation to replicate this aesthetic in album form. Not only could No.6 Collaborations Project substitute for a cannily constructed cross-genre play list, each of its tracks could be swapped into any mood-based play list -- something that's true not only of the chill hip-hop/folk hybrids but the blaring closer, "Blow," a churning rocker featuring both Chris Stapleton and Bruno Mars. This pairing shows how savvy Sheeran is in his choice of collaborators: Stapleton brings him a country audience he heretofore ignored, while Bruno is one of the few pop stars as big as the ginger man himself. Throughout No.6 Collaborations Project, he slyly targets different demographics in this fashion: Camila Cabello and Cardi B show up on "South of the Border," "Cross Me" has Chance the Rapper and PnB Rock, Justin Bieber is on "I Don't Care," while the presence of Eminem and 50 Cent on "Remember the Name" makes it feel like a conscious throwback. The cast of characters suggests a wilder album than No.6 Collaborations Project is, but that's a deliberate choice on Sheeran's part. Its glassy, placid groove isn't a reflection of his blandness, but how Sheeran knows that this is the sound that defines global pop in 2019. ~ Stephen Thomas Erlewine