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The markings DBxA20 and SY6633 identify the specific needle system, meaning the shank dimensions, length and scarf shape that fit certain industrial lockstitch/chainstitch machines (often high‑speed or specialized units).
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This system is not interchangeable with common systems like DBx1 or DCx1; using the wrong system will prevent proper clamping and can cause skipped stitches or needle breakage.
Size and fabric use
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The marking 19/120 indicates the needle size: 19 is the Singer/US size and 120 is the metric size.
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A size 120/19 needle is quite heavy, generally intended for thick materials such as heavy canvas, multilayer denim, tarpaulin, webbing, or technical textiles with correspondingly thick thread.
Practical notes for your machines
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Only use these needles on machines whose manuals or needle bars specify DBxA20 / SY6633; do not mix them with DBx1 or DCx1 stock in the workshop.
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Because of the large size 120/19, they are best reserved for heavy‑duty operations, not for standard garment-weight woven or knit fabrics.
