Weltool M4-365 "Blue Faced Beast" 365nm UV Black Light Flashlight
The Weltool M4-365 "Blue Faced Beast" (M4-365) is a high-power 365nm UV-A black light flashlight engineered for professional fluorescence work. At high output it reaches an enormous 14,000mW of UV radiant flux across a large irradiation area, with a switchable low mode for finer control. A patented through-hole cooling structure, black filter-glass lens, and CNC-machined T6 aluminum body make this ultraviolet flashlight ideal for UV curing, non-destructive testing (NDT), fluorescent leak detection, mineral exploration, forensic evidence collection, and document anti-counterfeiting inspection.
Highlights
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True 365nm UV-A LED – up to 14,000mW radiant flux, far stronger fluorescence than 395nm blacklight flashlights
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Two output modes – high-power and low-power, switched from the tail
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Black filter-glass lens removes stray non-365nm light for a pure UV beam
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Patented through-hole cooling plus temperature protection for sustained high output
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21700 battery and portable charger included – field-ready out of the box
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IP67 waterproof, 1 meter drop tested, hard-anodized CNC T6 aluminum
Output & Runtime Chart
| Mode |
Output |
Beam / Wavelength |
Runtime |
| High |
14,000mW UV radiant flux |
365nm UV-A (invisible) |
Auto step-down after 3 min to protect against heat |
| Low |
Reduced radiant flux |
365nm UV-A (invisible) |
Extended runtime for close inspection |
Static output tested by Weltool with an INR21-40P 21700 lithium-ion battery at ~20°C; results vary by environment. Exact low-mode radiant-flux figure and per-mode runtimes are not published numerically by the manufacturer.
Specifications
| Emitter |
High-power UV-A 365nm LED (~10,000 hr lifetime) |
| UV output |
Up to 14,000mW LED radiant flux (high) |
| Wavelength |
365nm (invisible UV-A) |
| Lens |
Black filter tempered glass; aluminum reflector |
| Battery |
1 × 21700 rechargeable Li-ion (included) |
| Charging |
Included portable USB charger (external) |
| Switch |
Tail forward-click switch (>10,000 presses) |
| Protection |
Reverse-polarity, over-discharge, low-battery warning, temperature |
| Waterproof |
IP67, usable in heavy rain; 1 meter drop tested |
| Dimensions |
35mm head × 26.5mm body × 154mm length |
| Weight |
153 g (without battery) |
| Finish |
CNC T6 aluminum alloy, hard anodized |
What's in the Box
- Weltool M4-365 365nm UV flashlight
- 1 × 21700 Li-ion battery
- Portable charger
- Stainless steel pocket clip
- Spare O-ring
Frequently Asked Questions
What wavelength is the Weltool M4-365, and why does 365nm matter?
The Weltool M4-365 (M4-365) emits true 365nm UV-A light. 365nm triggers stronger, cleaner fluorescence with less visible glow than 395nm lights, so the Weltool M4-365 reveals targets with far higher contrast for professional inspection.
How powerful is the Weltool M4-365?
The Weltool M4-365 (M4-365) delivers up to 14,000mW of UV radiant flux on high – among the most powerful handheld 365nm UV flashlights available, covering a large irradiation area.
What can the Weltool M4-365 detect?
The Weltool M4-365 (M4-365) reveals scorpions, pet urine and stains, coolant and refrigerant leaks (with dye), minerals and gems, forensic body fluids, and counterfeit security marks on currency and documents.
Is the Weltool M4-365 safe, and do I need eye protection?
365nm light from the Weltool M4-365 (M4-365) is invisible and intense. Always wear professional UV-protective glasses, never shine it at people, eyes, skin, or reflective surfaces, and keep the Weltool M4-365 away from children.
What battery and charging does the Weltool M4-365 use?
The Weltool M4-365 (M4-365) ships with a 21700 rechargeable Li-ion battery and a portable charger, so it is ready to use out of the box.
Is the Weltool M4-365 waterproof and rugged?
Yes – the Weltool M4-365 (M4-365) is IP67 rated for use in heavy rain and passes a 1 meter drop test in a hard-anodized CNC T6 aluminum body.
What is the Weltool M4-365 used for?
The Weltool M4-365 (M4-365) is used for UV curing, NDT, fluorescent leak detection, mineral exploration, criminal investigation and evidence collection, and anti-counterfeit document inspection.
Where can I buy the Weltool M4-365?
You can buy the Weltool M4-365 (M4-365) at Going Gear, an authorized Weltool dealer.
