What This Lamp Is
STL101RFBP is a combination stop, turn and tail lamp for trailers. It uses a 12-diode LED board behind a red lens in a standard 4-inch round body, with a flange built into the housing so it bolts to the trailer's existing bracket or light pocket. No grommet required, no separate mounting ring to chase down.
The lamp carries an integrated reflex reflector, so one unit covers stop, turn, tail and reflector duty at that corner. That matters on a DOT walkaround — an inspector looking at the rear of the trailer sees one compliant assembly rather than a lamp plus a stick-on reflector that has half fallen off.
Electrically it's a 12V, 12W solid-state design. Current draw is lower than an incandescent bulb setup, and there's no filament to shake apart on washboard gravel or a rough yard. The housing is sealed to IP67, which is why this style shows up on boat trailers where the rear lamps go under water at the ramp.
Why These Numbers Cross
The Optronics number STL101RCFBK crosses to STL101RFBP because both describe the same physical lamp: 4-inch round body, flange mount, 12 LEDs, red lens, 12V stop/turn/tail function with reflex reflector. Same bolt pattern, same lens diameter, same three-wire function set. That combination is what makes a lamp interchangeable at the bracket.
Trailer lighting numbers usually encode the family, the lens color, the mount style and the connector or pigtail arrangement. Change the mount from flange to grommet and the number changes even though the optics are identical. That's why two numbers can look unrelated on paper and still drop into the same pocket — you're comparing suffixes, not products.
That number is listed here for identification only. PartStop is not affiliated with, endorsed by, or authorized by Optronics or any other manufacturer. Use the cross as a starting point, then confirm against the number molded or labeled on the lamp you're pulling off.
Check Before You Order
Pull the old lamp and read the back of the housing. Trailer lights get swapped by whoever had one on the shelf, so the number on the unit you're removing tells you more than the trailer build sheet does. Confirm it's a flange mount and not a grommet-mount lamp pushed into a rubber ring, because those are not interchangeable without changing the bracket.
Then check the wiring. This is a three-function lamp — ground, tail and stop/turn. If the trailer corner currently runs a separate turn lamp and a separate tail lamp, you're changing the circuit layout, not just the bulb. Also verify the system is 12V; this lamp will not survive a 24V feed.
STL101RFBP Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to STL101RFBP. Use them to identify the part — then confirm the exact fit by VIN or the number stamped on your old unit before you order. An interchange is a starting point, not a fitment guarantee.
| Brand / Line | Cross-Reference Numbers |
|---|---|
| Optronics | STL101RCFBK |
Frequently asked questions
Will STL101RFBP fit where a grommet-mount 4-inch round light was?
Not directly. A grommet-mount lamp sits inside a rubber ring pressed into a panel hole; a flange-mount lamp bolts flat to the surface or bracket. The lens diameter is the same but the mounting is different. Check what you are pulling off before ordering, and confirm the bolt spacing on your bracket.
Is STL101RCFBK the same lamp as STL101RFBP?
It crosses to the same 4-inch round flange-mount stop/turn/tail LED. The cross-reference is a starting point, not a fitment guarantee. Confirm by matching the number printed on your old lamp and by verifying the mount style and wiring function set on your trailer.
Why did my last LED trailer light fail if there's no filament?
Usually water and ground, not the diodes. A cracked lens seal or a chafed pigtail lets moisture into the board and corrodes the traces. A rusted ground stud or a bad white wire connection also makes LEDs flicker or read dim. Clean the ground and check the harness before you condemn the lamp.
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Run your VIN and we’ll match parts to your exact truck, or call the counter — a person who knows trucks verifies fitment by OEM number before the order ships. No wrong-box returns.
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