Lululemon | EUC size med(?) | black halter workout top. Tie back. Long length

Lululemon used workout shirt. Stretchy fast wicking fabric. Unique design with backless design. Three straps with braid. The back around neck. Built in shelf bra. Long length that flares out a bit. Light black. I can’t find the size I’m not sure if it’s a small or a medium. Excellent used condition.