21 circuits across three rows — what the 4.50 mm pitch means for your harness
The JST YLP-21V is the 21-position, triple-row plug in the YL series, pitched at 0.177" (4.50 mm). That pitch is wide enough to keep 20-22 AWG wire routing manageable in a harness without forcing a bulky connector body — the 3-row layout packs 21 circuits into a footprint that a 2-row design would need more board edge for. This is a housing-only part — contacts are not included. You'll need the YL-series female crimp socket terminal ordered separately.
Where this plug fits in the YL series
The YL series covers 2 to 21 positions in single, dual, and triple rows. The YLP-21V sits at the top end of the position count — it's the highest-density member of the series, using all three rows to reach 21 circuits. The 4.50 mm pitch is common across the series, so the contact crimp tooling and terminal part numbers are shared. If your BOM calls for fewer circuits, the 12-position YLP-12V (2-row) or 8-position YLP-08V (2-row) are the direct lower-position siblings — same pitch, same latch lock, same terminal.
What the operating temperature tells you about where to use it
Rated -25°C to 90°C. That covers most indoor industrial cabinets, consumer electronics internals, and automotive passenger-cabin harnesses. It does not cover engine-bay heat (125°C+), outdoor direct-sun enclosures in hot climates, or cold-storage below -25°C. If your application lives inside those bounds, the YLP-21V is a solid fit for a crimp-terminated, latch-locked free-hanging interconnect.