See 122.
In addition to the markings required in 244.2 for First-Class Mail International items, in 254.2 for First-Class Package International Service items, and in 234.2 for Priority Mail International parcels, free matter must be marked “Free Matter for the Blind or Handicapped” in the upper right-hand corner of the address side of the mailpiece.
Matter for the blind must not be sealed, even if registered.
Free Matter for the Blind or Other Physically Handicapped Persons items mailed under 270 are not sealed against inspection (see ASM 274). Items must be prepared in such a way that the contents are protected but inspection of the contents is not hindered.
The items must be placed in wrappers, in rolls, between cardboard, or in bags, boxes, unsealed envelopes, or containers. Dangerous fasteners may not be used. The articles may also be tied with string or twine in a manner that will permit them to be easily untied.