New Yorkers have some very specific needs when it comes to a commuter bag: durability, comfort, and professionalism. The traditional briefcase might look good in the board room, but that fine Corinthian leather is just going to get scratched on the train or the sidewalk. The ubiquitous nylon messenger bag is durable enough, and you can get away with it at the office, but if you're carrying a heavy load (say, your laptop) your shoulders will feel it. (Besides, it's not good to walk around with your weight unevenly distributed.) A backpack will be comfortable on that one-hour-standing-on-the-train commute, but you'll look like you just came from Freshman English class.

I saw an ideal solution at Tumi -- a backpack that converts to a briefcase. Unfortunately, I don't have $350 to blow. (They make a cheaper one in their T-Tech line but it's still $225, and it's uglier, and it screams "computer bag"). There's a line of similar convertible bags at BBG which at $100 are far cheaper (found on Cool Tools, where you really must read this "pedantic" review of the $530 William Gibson Aviator Bag and ensuing flame war against Bruce Sterling, the new curator there).

But I really like the bag I picked up at the MOMA Design Store: the Lexon Challenger Backpack. It's well made and well designed. As a backpack it's comfortable -- I carried 16 lbs of gear around Manhattan yesterday and my shoulders feel fine. (There's a chest compression strap if you need it.) It's got two main compartments (one with a padded laptop section) and three front pockets. Inside are pen loops and a card holder and a change purse and a carabiner hook so you can squirrel things away properly. I especially like the top corner pocket, which is great for a cell phone stash (or any other gear you want quick access to.)

When you've arrived and are ready to attend your meeting, you just unclip the back straps and slip them inside a zippered compartment. A handle slides out of the top. Now you've got a briefcase. The bag is neutral gray, and most importantly, doesn't have patches, logos, or dingbats on it, other than a subtle black branding box.

And it's only $100. (Less if you're a MOMA member.) Strangely, MOMA isn't marketing the bag's main feature, that it converts from a backpack to a laptop. Update your ad copy, guys!