Glass to glass:
29-5/16" width
11-1/2" depth
Bottom glass to black frame:
17-3/4" height
Just be aware that the added height of the 29 over the 20L wil give you less room in the cabinet if it is going underneath unless you go with a higher than normal stand. And I'll tell you that I made the baffles in mine too high, if I did it again I'd be sure to make the highest about 3 or 4" below the top to reduce salt creep.