See if this works with your machine
The Big Book of Serging is a guide to BERNINA Overlock Machines. A reference book that any overlock owner can use, this book features current BERNINA and Bernette serger models including the new L 8 Series overlock machines.
From Threading to Decorative
Full of information about how BERNINA overlock machines work, this book covers practical and creative subjects such as seaming options, gathering methods, and decorative serging techniques. You can also read about the basics of threading, details about available presser feet, and everyday techniques such as starting and ending serged seams.
Get Inspired!
With lots of inspirational photos, you’ll get excited about all the great things you can do with your overlock machine. From garments to quilts, to craft projects, an overlocker lets you sew them faster with more professional results. You’ll find serging techniques such as zipper applications, piping, binding and hems to use on almost any project you want to make.
A Great Reference
The Big Book of Serging has details about the many stitch variations found on the BERNINA overlock machines. Each type of stitch, such as overlock, flatlock, coverstitch, etc. has a chart that shows the variations of the stitch and the most common settings used for those variations. There are also technique charts such as the one below showing the stitch settings for gathering and elastic applications.
Part Number: BER BBOS
Guaranteed to fit because it is a 
part.