Don; There are a lot of threads about the MES in this section. You will get a feel for them if you read these.
The Masterbuilt web site is erroneous about the dimensions of their product...it seems untidy of them to quote the thing as smaller than it actually is but that is their business I guess
Outside dimensions of their smoker is 13 3/4" X 17" X 30 1/4 not including the door....just the box
Inside shelf dimensions are 12 3/4 X 15 1/4 X 4" verticle clearance if you use all 4 shelves at the same time....so by removing shelves you can go to 8" 12" or 16" verticle by having less shelves
capacity is good for a single family and there has been little complaining about the size.....I can do a 14# turkey easily or 4 racks of BB ribs easily
There are a few older models out there yet that are not vented on top and have a different door
seal and no door latch...avoid it...get the newer model or don't buy it....if it has a door latch and top vent then it is the newer model.....also Sam's club has a special addition which is larger yet but it tends to be pricey ($300)...the others can be obtained for ($200) at most places.
hope this helps