If there’s a single must-have top for spring, it’s got to be a soft and slouchy number from T Alexander Wang.

The structured styling and body-conscious cuts of Wang’s fall 2009 collection shown at New York Fashion Week this week may have wowed fashion critics as a daring departure from the designer’s usual territory, but fans of the 24-year-old designer’s previous collections will find that the new diffusion line closely mimics the loose fit and just-woke-up appeal of the earlier work by the San Francisco native. What’s more, the new line’s racer-back tanks, halter tank dresses and short-sleeve tees ring in at about a third of the price ($65-$95).

Pair with skinny jeans and heels or a skirt and boots for a stylish take on ultra-casual. Also perfect for layering, the basic tanks and tees are available in rayon and cotton in colors such as charcoal, white, black, lavender and chartreuse.

Available at Carrots, 843 Montgomery St., 415-834-9040, www.sfcarrots.com