In the teardown, all I see are large Phillips screws:

This probably uses a #2 or #3.

Black and Decker AS150 Steam Advantage Iron Teardown

While screw size is shrouded in mystery, there are four basic sizes of Phillips screwdriver — from #0 to #4 — #0 being the smallest. The most common sizes are #2 and #1, #2 for standard screw sizes, #1 for “miniature”. Then there are the jeweler-size screws.Jan 18,