All US bank notes have a width of 2.6 inches.
The Deep Carry Tube (2.6) was originally made for the carry and concealment of 10 x $100 dollar bank notes = $1,000 also known as a Grand, or a “G”.
Deep Carry Tubes are designed to be portable and conveniently carried.
https://www.etsy.com/uk/listing/4300098981/deep-carry-tube-26-6-pack