With Filestar you get 73 different skills for working productively with Sound Designer II File (.sd2f) files.
About .Sd2f
Name
Sound Designer II File
Extension
.sd2f
Format
Binary
Category
Audio
Developer
Avid Technology
Description
The Sound Designer II audio file stored with the .sd2f extension, which comes from the format's classic Mac OSType "Sd2f" and appears instead of .sd2 on files that have passed through Mac software. The format is the same Digidesign/Pro Tools big-endian PCM audio as .sd2.