RL0402E012M300K from RUILON Shenzhen Ruilongyuan Elec, in a 0402. Pinout and pin descriptions extracted from the manufacturer datasheet by ds2sf; symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin	Name	Type	Function
1	A	passive	Terminal electrode 1 of the metal oxide varistor. Bidirectional/symmetric: the two terminals are electrically interchangeable. Connect between the protected line and the reference (typically ground) to clamp ESD/transients above the ~200 V trigger voltage down to ~50 V.
2	B	passive	Terminal electrode 2 of the metal oxide varistor. Bidirectional/symmetric: identical function to terminal 1. Typically routed to the signal line (or ground) opposite terminal 1 for shunt ESD protection.

Key specifications

Parameter	Value
Manufacturer	RUILON Shenzhen Ruilongyuan Elec
Package	0402
Category	Circuit Protection
Pins	2

Ordering variants

Same part, different packaging or reel option.

RL0402E012M300K

CAD (KiCad official)

Symbol: RL0402E012M300K
Footprint: Resistor_SMD:R_0402_1005Metric
3D model: 0402 (KiCad packages3D, STEP)

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

Datasheet: RUILON Shenzhen Ruilongyuan Elec datasheet (7 pp, sha256 4986f3f7e248068a, retrieved 2026-08-17, tier: lcsc)
Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF