Overlock knife/blade compatible across the modern overlock family (JACK E4S/E5/C-series, Speedway SW6/SW7, and equivalents). Knives cross thread counts within the family. The Upper Looper (Part #20717004) is a genuine JACK original replacement part designed for JACK E4s, C6, C7 and 798T series overlock machines, as well as Siruba 700K, 700L, Speedway SW 7D and Juki MO6800 series models. Manufactured to OEM specifications for precise fit and reliable performance. Equivalent Part Numbers JACK: 20717004 SIRUBA: LP226 JUKI: 70000798 Compatible Machines This part fits the following industrial sewing machine models: JACK: E4s series, C6 series, C7 series, 798T, E4, C3, C4, C5 series (Except H, M, A04, 435 model), E4S-4, E4S-3-32R2, E4S-5-03, E4S-6-03, C7-4, C7-5, C7-3-02, E4S-3-02, C7-6-03/333 Urus, E5-3-32R2, E5-5-03, JK-798D, JK-904E, JK-798T, JK-799S SIRUBA: 700K, 700L series, 747, 757 SPEEDWAY: SW 7D series, SW7-4D, SW7-5D, SW6-4D, SW6-3D, SW6-3D-32R, SW6-5D, SW6-6D JUKI: MO6800 series, MO-6714, MO-6716, MO-6814, MO-6816 PEGASUS: M700, EX5200 BROTHER: 3034 Technical Specifications Brand JACK Part Number 20717004 Part Type Loopers Condition New – OEM Original Looking for a replacement upper looper for your JACK E4s or C6 overlock machine? This genuine OEM part is also compatible with Siruba 700K, Speedway SW 7D and Juki MO6800 series machines. Shop with confidence — all parts ship from Miami, FL. ⚠️ Compatibility Notice: Always verify your machine model and subclass number before ordering. Part numbers and compatibility are provided as a reference only. Supra Sewing is not responsible for purchases made without confirming compatibility with your specific machine. All sales on replacement parts are final.
