question on W2 heads

Mine too, I found the ones with a hex / allen head are better to use, better to tighten with an Allen wrench . I always felt I couldn't get the ones using a standard flat head screw driver tight enough.
Get them with Torx type heads if you can find them. A lot less likely to strip out than hex. I can't tell you how many I had to use a punch, chisel, or drill on over the years, especially stainless. Torx can take a pretty good beating and the drivers seem to torque out less than hex or God help you, a Phillips.