The mSATA SSD unit appears to be assembled by Toshiba and is model number THNSNC064GMDJ.

There are six main chips on this custom board:

Four Toshiba TH58NVG7D7FBASB 16GB flash chips which make up the total 64GB.

Toshiba T6UG1XBG Solid State Drive controller.

Micron OKA17 D9HSJ DDR DRAM cache.

The new SSD is 2.45 mm thick compared to the platter-based 5.12 mm thickness of the old Air's drive. Being smaller in two of three dimensions definitely helps the new Air achieve a super-slim profile.

The SSD weighs in at a mere 10 grams, compared to the 45 grams of its spinning cousin.