The 8.5 × 3.69 in letter fold
A Letter sheet folded twice into three horizontal bands, closing to a wide, short 8.5 × 3.69 in piece.
Closed size8.5 × 3.69 in
Opens to8.5 × 11 in
Fits#10 envelope
FilesLayered PSD, smart objects
It's the fold built for the mail. Folded this way a Letter sheet fits a #10 business envelope without trimming, which is why it carries direct mail, invoice and statement inserts, self-mailers, appointment reminders and take-away menus — anything that has to be printed on ordinary stock, folded on a standard machine and posted cheaply.
What makes it different to design is the panel shape. Most folded brochures give you tall narrow columns; here the panels are wide landscape strips, roughly 8.5 by 3.7 in each. Text runs in long lines rather than columns, images want panoramic crops, and a tall photo or a stacked layout simply won't fit — so it works best as three clear bands, each with one message. It also reveals itself in stages as it opens, so the order the panels appear in is worth settling before anything gets placed.
In the sets: closed, mid-open and laid flat from above, so you can present the folded piece and the full open sheet together. Each is a layered PSD with smart objects — the artwork sits on its own layer, so replacing it leaves the folds, lighting and shadow untouched.