Conversion of sit files to 1 file format

It seems that both .sit and .1 files are or were in the past associated as Stuffit compressed archives. As such, your best option to extract/convert any of these would be to use the original software. Considering the limited support for SIT format, it is unlikely it works in 3rd party apps.

Open SIT file    Open 1 file

Related software

StuffIt Deluxe icon

StuffIt Deluxe

A commercial compression utility

StuffIt Deluxe for Mac icon

StuffIt Deluxe for Mac

A backup and archive utility

StuffIt for Mac icon

StuffIt for Mac

Mac version of the popular utility