The strap is only attached at the top. It doesn't convert to a backpack. The measurements are 8.5"H x 6.75"W x 2.75"D
http://forum.purseblog.com/coach/id-coach-item-post-any-coach-item-name-355205-440.html#post24982156
Found it - Flap Drawstring from the Lightweight line, style number 4029 from around 1991-92.