What this 4-position unshrouded header does
The 3-641212-4: This is a single-row, 4-circuit header from the MTA-100 series, designed to connect a board to a wire harness.
Mounting and orientation fit
The insulation height is 0.100" (2.54mm), and the mating pin length is 0.295" (7.49mm) — enough to engage the receptacle's contact beam fully.
The base product number is 641212, so any variant starting with that prefix shares the same tooling and footprint.
