Then why only 4 stars?
Yes, they work great but Tyvek is an unusual material for an envelope.
People are not accustomed to seeing small envelopes like this. But I do recommend them.
One
additional note because of the review of the black Himber Tyvek vertical envelope.
The inner
flap, as the envelope comes, may be a bit noticeable to the spectator when you open the envelope to
slide the card, note, whatever out. Here is the fix:
Take a glue stick (strong glue) and a
toothpick. Using the toothpick glue the back of the inner flap which is loose. Press the flap
against the back of the envelope and the visible flap become invisible and matches the top seam of
the outside flap.
As for the shape of the flap and the horizontal slit, I really don't have a
problem.
As for the "unaesthetic" look of the slit, I really don't think the spectator gets much
of a look at it. You pull out a piece of paper or a card (which does work in the envelopes) and
that's where the attention is.
Which is better: brown or black envelope?
If you are
using the envelope inside a black wallet, I'd say use the brown for color contrast.