ACR Firefly PRO Waterbug SOLAS Strobe Light — Auto Water-Activated, 3-Mode, 41cd | ACR 3971.3 flagged -price issue
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The ACR Firefly PRO Waterbug SOLAS Strobe Light 3971.3 is a compact emergency rescue strobe designed for high-visibility marine distress signaling. Unlike the manual Firefly PRO SOLAS model, the Waterbug version includes water activation sensors for automatic activation when submerged, while still offering selectable strobe, steady-on, and SOS modes for emergency recovery situations. It uses a cool white LED with wide 360° light emission, 41 candela strobe output, and visibility of over 3 miles.
Key Features
- ACR part number 3971.3 — Firefly PRO Waterbug, carded version.
- Water-activated SOLAS emergency strobe with built-in water sensors.
- Three selectable modes: strobe, steady-on, and SOS.
- 41 candela / 257 lumen strobe output with cool white LED.
- Visibility rated at over 3 miles.
- Runtime: 56 hours strobe, 28 hours steady-on, and 30 hours SOS.
- Size: 4.4" x 2.2" x 1.2" / 11.7 x 5.7 x 2.8 cm.
- Weight: 2.43 oz / 69 g without batteries.
- Factory tested waterproof depth: 33 ft / 10 m.
- Requires AA batteries.
- Includes Velcro webbing for mounting.
- Approvals shown for the Firefly PRO Waterbug include SOLAS, USCG, IMO LSA, CE, and MED.
Intended Use
The Firefly PRO Waterbug is intended for emergency visual signalling on life jackets, inflatable PFDs, ditch bags, rescue gear, commercial marine safety kits, and personal survival equipment. Its automatic water activation makes it especially useful where fast activation may be needed during man-overboard or abandon-ship situations.
Fitment Notice
This is the Waterbug SOLAS version of the ACR Firefly PRO series. For applications that require manual-only operation, use the Firefly PRO SOLAS 3970.3 version instead. Always confirm the approval requirements for your vessel, operating region, and onboard safety-equipment list before replacing or adding emergency signalling gear.
When This Product Needs Replacement
Replace the strobe if the housing is cracked, the battery compartment shows corrosion, the switch or water-activation function is unreliable, the light output is weak, or the unit fails a routine safety check. Batteries should be inspected and replaced regularly, especially before offshore use, seasonal launch, or long-term storage.
Installation Notes
Mount the Firefly PRO Waterbug where it can activate and be seen quickly in an emergency, such as on a life jacket, PFD, belt, pack, or survival kit. The Waterbug operating instructions show that the unit can be turned on or off with the thumb switch, modes are changed by toggling the switch, and water contact activates the strobe function when armed. Keep the battery-door O-ring clean and free of debris to maintain watertight integrity.
Alternate/Superseded Part Numbers
Related ACR Firefly PRO references include:
- 3971.3 — Firefly PRO Waterbug, carded
- 3971.4 — Firefly PRO Waterbug, bulk
- 3970.3 — Firefly PRO SOLAS, carded, manual activation
- 3970.4 — Firefly PRO SOLAS, bulk, manual activation
Parts Desk Insight
The main reason to choose 3971.3 is the automatic water activation. For life jacket and man-overboard use, that feature can matter more than it looks on the shelf because the light can begin signaling even when the wearer cannot manually activate it right away.
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
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If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
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