Measure before you open the range
Use fill only on the carton side of the mailroom.
Void fill belongs beside a carton, not inside a mailer that should have been a closer bag. The page for Void fill is where Packaging Suppliers shows that line.
The published limit, if there is one
Loose fill and paper fill take a gap in a box. A mailer that is too big should be a smaller mailer.
Buying fill to plump a slack mailer fights the reason you chose a bag.
Write the size down
Name the fill on its own line.
At Packaging Suppliers, Void fill does not change the cutoff. Orders by 3pm leave the same day. Under £50 ex VAT the delivery is still available. It is just not the free threshold.
Open Void fill when you already know this line. The sack or the pack is the unit on the page. Packaging Suppliers will still dispatch an order placed by 3pm on the same day.