E16 + 25T use for Thin Fabric, usually use with Size #10, #11 Needles;
E18 + 25T use for Thin-Medium Fabric, usually use with Size #11, #12 Needles;
E20 + 18T use for Thin-Medium Fabric, usually use with Size #12, #14, #16 Needles;
E22 + 18T use for Medium-Heavy Fabric, usually use with Size #14, #16 Needles;
E24 + 18T use for Medium-Heavy Fabric, usually use with Size #18, #19, #20 Needles;
E26 + 18T use for Heavy Fabric, usually use with Size #19 ~ #21 Needles;

Compatible With Most Industrial 1-Needle Lockstitch Sewing Machines;
Artisan : 196R, 5550N, 8500N, ZJ-100;
Brother : B705, B707, B715, B716, B737, B738, B755, B757, B758, B781, B790, B792, B795, S6200A, S7200A, S7200B;
Consew : 210, 218, 219, 220, 230, 290, 310, CN2230;
Juki : DDL-127, DDL-227, DDL-500, DDL-555, DDL-555-5, DDL-5530, DDL-5550, DDL-5550-6, DDL-5550N-7, DDL-8300, DDL-8500, DDL-8700, DDL-8700-7, DDL-9000, DLM-522, DLM-5400, DLN-412, DLN-415, DLN-415, DLN-5400N-7, DLN-5410N-7, DLN-5490N-7;
JACK : JK-8900D, JK-8995DY, A2, A3, A4, A5, A6;
Singer : 120U, 121C, 121D, 191D, 241, 251, 281, 366K, 400W, 402W, 451K, 491D, 591D, 600W, 660A, 691D, 770D, 771D, 2491D;
Siruba : L818, L819;
TACSEW : 5550, 8500, T8700;
YAMATA : FY8500, FY8700;
ZOJE : ZJ5580-5-D3, ZJ8500-D3, ZJ9701, ZJ9800A-D3B;

And Also Fits Many More Other Standard Industrial Single Needle Lockstitch Sewing Machines.