iMore’s mock-up (left) of smaller iPad, with iPad 3 and iPhone

FORTUNE — Daring Fireball‘s John Gruber, a blogger with unusually good sources at Apple AAPL , has combined his own assumptions with what he’s heard from his “little birdies” to draw the most complete picture yet of the purported iPad Mini.

“Mini” is what most Apple watchers — including Wall Street analysts — have been calling to the next iteration of Apple’s tablet computer.

But given what he believes will be the device’s most salient features — markedly thinner and lighter than any competing device — Gruber suggests it might better be marketed as the iPad Air.

It’s a long thoughtful post and worth reading in the original here.

I’ll just add two things:

  • The mock-up above, created by iMore‘s Rene Ritchie, which Gruber believes is the most accurate depiction of the device he describes
  • The list below, drawn from a longer one posted by MG Siegler on his Paris Lemon blog, comparing Gruber’s estimate of the weight of the iPad Air with the weight of other mobile devices.

iPod touch: 101 grams
iPhone 4S: 140 grams
Kindle (WiFi): 170 grams
iPad Air (Gruber’s estimate): 265 grams
Nexus 7: 340 grams
Kindle Fire: 413 grams
New iPad (WiFi): 652 grams

Click here for the rest of Siegler’s list.