Description
The SureFire M640DF Dual Fuel Scout Pro is a rifle weapon light that gives you a choice of power source, which is the whole point of "Dual Fuel." It runs 1,500 lumens on the included SF18650 rechargeable lithium-ion battery, or 1,200 lumens on two CR123A primary batteries. That flexibility matters in the real world: run the rechargeable day to day to save money, and keep CR123A primaries on hand as backup that never go dead sitting on a shelf. It builds on the combat-proven M600DF platform with SureFire's updated Scout Pro body.
The beam is a hybrid pattern from a TIR lens: a usable center with plenty of surround spill, so it lights up a room or a tree line and still reaches out. On the SF18650 it pushes 16,000 candela to about 250 meters. This is the flood-leaning Dual Fuel, not the Turbo (more on that below), so it's the better pick if you want broad, situational-awareness light rather than a narrow long-throw beam.
It mounts with SureFire's Low-Profile Mount (LPM), which lets you position the light exactly where you want it on the rail and ships with cleats for both MIL-STD-1913 picatinny and M-LOK, so it goes on most modern handguards without an adapter. It's built from aerospace aluminum, Mil-Spec hard anodized, O-ring sealed, and rated IPX7. Activation is the included Z68 momentary/constant-on pushbutton tailcap with a protective shroud.
Browse our full range of weapon lights and switches if you're building out a rifle.
Dual Fuel vs Dual Fuel Turbo
If you're deciding between this and the M640DF Turbo, here's the honest difference. This standard Dual Fuel is the flood option: 1,500 lumens with a hybrid beam and 16,000 candela, best for close to medium range and lighting up a wide area. The Turbo trades that spread for a tight, high-candela throw beam that reaches much farther but lights up less around your target. For most rifle work indoors and at normal distances, the standard Dual Fuel's hybrid beam is the more usable light. Choose the Turbo if maximum reach is your priority.
Add a Remote Switch
Want to run a tape switch instead of the rear pushbutton? You'll need to swap the tailcap and add a switch. Important: to get the full 1,500-lumen output from a remote switch on this Dual Fuel light, you need SureFire's UEE cap, not the standard UE cap. The standard UE tailcap works on this light only when running CR123A primaries, because the high-output 18650 mode requires the UEE's different spring and chip. Once you have the right cap, a tape switch like the SureFire ST07 plugs in, and the Magpul M-LOK tape switch mount keeps the pad positioned on your rail. Browse the full remote switches selection for more options.
Other Scout Lights We Carry
If you don't need the dual-fuel flexibility, the M640U Scout Pro is the standard single-fuel version. For a smaller, lighter option, the M340C Mini Scout Pro shrinks the footprint. Keep spare CR123A batteries on hand as backup fuel.
Key Features
- Dual fuel. Runs the included SF18650 rechargeable or two CR123A primaries.
- 1,500 / 1,200 lumens. 1,500 on SF18650, 1,200 on CR123A.
- Hybrid TIR beam. Usable center with broad spill for close to medium range.
- Low-Profile Mount. Optimized positioning, includes both 1913 and M-LOK cleats.
- Z68 tailcap. Momentary and constant-on pushbutton with protective shroud.
- Mil-spec build. Aerospace aluminum, hard anodized, IPX7 sealed.
Specs
- Output: 1,500 lumens (SF18650) / 1,200 lumens (CR123A)
- Runtime: 1.5 hours (SF18650) / 1.25 hours (CR123A)
- Peak beam intensity: 16,000 candela (SF18650) / 12,800 candela (CR123A)
- Beam distance: 250 m (SF18650) / 220 m (CR123A)
- Battery: One SF18650 rechargeable (included) or two CR123A lithium
- Mount: Low-Profile Mount, MIL-STD-1913 and M-LOK cleats included
- Switching: Z68 momentary / constant-on pushbutton tailcap
- Construction: Aerospace aluminum, Mil-Spec hard anodized
- Sealing: IPX7
- Length: 5.56 in
- Weight: ~5.5 oz with batteries
- Made in the USA
FAQ
What does "Dual Fuel" mean?
The light runs on either the included SF18650 rechargeable lithium-ion battery or two CR123A lithium primaries. You get 1,500 lumens on the rechargeable and 1,200 on CR123A. The flexibility lets you use the rechargeable normally and fall back to shelf-stable primaries when needed.
What's the difference between this and the Turbo?
This standard Dual Fuel has a hybrid flood beam (1,500 lumens, 16,000 candela) that's better for close to medium range and wide-area lighting. The Turbo has a tighter, higher-candela beam for more throw at distance. Pick this one for usable spread, the Turbo for maximum reach.
What rails does it fit?
The Low-Profile Mount includes cleats for both MIL-STD-1913 picatinny and M-LOK, so it mounts to most modern handguards without an adapter.
Can I run it on a tape switch?
Yes, but to get full 1,500-lumen output from a remote switch on this Dual Fuel light, you need SureFire's UEE cap. The standard UE cap works only when the light is running CR123A primaries. After installing the correct cap, the SR07 or ST07 tape switches plug in.
Is the rechargeable battery included?
Yes. It ships with the SF18650 rechargeable battery. The 1,500-lumen output, 1.5-hour runtime, and 250-meter beam distance figures require that battery; on CR123A you get the 1,200-lumen numbers.
