1634DX 1634DX Features 3 or 4 Thread Serger This serger works with either 3 or 4 threads, for added flexibility. Up to 1,300 Stitches Per Minute Get more serging done in less time by sewing up to 1,300 stitches per minute. Durable Metal Frame Construction Durable metal frame allows your machine to tackle any project Easy to Thread Every Time Easy to follow, color-coded lay-in threading, and the lower looper threading system is designed to make sure the thread stays right in place Better Stitch Quality The differential fabric feed helps improve the stitch quality on virtually all types of fabric Removable Free Arm Simply slide off the removable arm to serge cylindrical items such as sleeves. Sew Easy with Brother Comparison Chart Comparison Chart 2340CV ST4031HD SDX125e Machine Type Cover Stitch Differential Feed Strong & Tough Serger ScanNCut Cutting Machine Included Stitches/Designs 3/4 Thread Function 3/4 Thread Differential Feed 682 Drawing & Cutting Designs Stitch/Design Selection Dial Selection Dial Selection 5" LCD Touchscreen Display Feature Easy Lay-in Threading Easy Lay-in Threading Built-in Material Scanner Attachments - Free Arm & Extension Table - Comparison Chart 2340CV ST4031HD SDX125e Machine Type Cover Stitch Differential Feed Strong & Tough Serger ScanNCut Cutting Machine Included Stitches/Designs 3/4 Thread Function 3/4 Thread Differential Feed 682 Drawing & Cutting Designs Stitch/Design Selection Dial Selection Dial Selection 5" LCD Touchscreen Display Feature Easy Lay-in Threading Easy Lay-in Threading Built-in Material Scanner Attachments - Free Arm & Extension Table -