On 25 Jan, 18:14, -MIKE- wrote:

The "lid" I refer to is from where you wrote...
"as there's a tie-bar between them above the saw blade, which
also acts as a further guard. "

So you infer "lid" from where I didn't write "lid".

The tie-bar is about an inch or so wide. It's vertically over the
blade. It's not a lid, and makes no attempt to keep fingers out of the
box. It's primarily there for structural reasons (my high-wall box is
far more stable than a low-wall sled), but it does also act as a guard
against long pieces of crossways timber dropping onto the blade, an
accident that's not implausible when cross-cutting.