What is the correct pentalobe screwdriver size for a Macbook Air Model A1370? I think it is 1.2 mm based on results returned by eBay, however, it would be nice if someone could confirm that this is the correct size and not the 0.8 mm

Macbook Air MacBookAir4,1 (11-inch, Mid 2011)

The goal is to remove the outer-lower casing (pentalobe screws) as well as the SSD screw (unknown screw type)
Based on information from iFixit, you need a P5 Pentalobe Screwdriver, which is 1.2mm, as shown in this MacBook Air 11" Mid 2011 Solid-State Drive Replacement guide to remove the lower case.

You need a T5 Torx driver for the SSD.