Shouldn't we keep it as a promise?
"Sentimental X's" features vocals from Leslie Feist, Amy Millan of Stars, and Emily Haines of Metric. Though all three had been featured on various Broken Social Scene tracks in the past, and taken turns as the group's live female vocalist from 2002 through 2004 on breaks from their other projects, this marks the trio's first studio appearance on the same song, albeit recorded separately.