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Ships within 48 hours · Estimated delivery Jul 5 - Jul 10
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Description
DAHUA ARD821-W2 Wireless Panic ButtonARD821 W2 Wireless Panic Button > Two way RF communication. > Provides multiple LED colors to indicate different statuses. > Cloud update and automatic recovery from update failure. > Offers accidental press prevention. > Battery life up to 5 years if used twice a week. > IP54 rated. Product Data Function Indicator Light 1 for multiple statuses (pairing, communication, and more) Remote Update Cloud update Button 1 Signal Strength Yes Low Battery
ARD821-W2
Wireless Panic Button
> Two-way RF communication.
> Provides multiple LED colors to indicate different statuses.
> Cloud update and automatic recovery from update failure.
> Offers accidental press prevention.
> Battery life up to 5 years if used twice a week.
> IP54 rated.
> Provides multiple LED colors to indicate different statuses.
> Cloud update and automatic recovery from update failure.
> Offers accidental press prevention.
> Battery life up to 5 years if used twice a week.
> IP54 rated.
Product Data
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Function |
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Indicator Light |
1 for multiple statuses (pairing, communication, and more) |
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Remote Update |
Cloud update |
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Button |
1 |
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Signal Strength |
Yes |
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Low Battery Detection |
Yes |
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Battery Level Display |
Displays battery level on app |
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Wireless |
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Carrier Frequency |
433.1 MHz–434.6 MHz |
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Communication Distance |
Up to 1,300 m (4,265.09 ft) in an open space |
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Communication Mechanism |
Two–way |
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Encryption Mode |
AES128 |
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Frequency Hopping |
Yes |
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General |
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Operating Temperature |
–10 °C to +55 °C (+14 °F to +131 °F) (indoor) |
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Operating Humidity |
10%–90% (RH) |
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Battery Model |
CR2032 |
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Battery Life |
3 years (if used twice a week) |
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Product Dimensions |
55 mm × 36 mm × 14.2 mm (2.17" × 1.42" × 0.56") (L × W × H) |
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Packaging Dimensions |
95 mm × 59.5 mm × 30.5 mm (3.74" × 2.34" × 1.20") (L × W × H) |
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Installation |
Wall mount; portable |
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Net Weight |
18 g (0.04 lb) |
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Gross Weight |
48 g (0.11 lb) |
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Certifications |
CE |
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Casing Material |
PC + ABS |
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Protection |
IP54 |
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Technical |
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Operating Current |
28 mA |
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Test Mode |
Yes |
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Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.4 ★★★★★
Based on 1618 reviews
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Product Reviews
★★★★★ 5
The perfect coffee mug warmer!
Color: Wood
If you need a coffee cup warmer for your desk or work-station, this is it! I've been using almost daily for several weeks now and zero complaints thus far.
As with many-a-reviewer, the problem I was trying to solve is my coffee going cold long before I was done with it, leading to repeated microwave rewarm sessions. After reading through numerous reviews, articles on the matter, and forum postings, I settled on this product. My requirements:
- I did not want to use a specialized cup
- I did not want to have to find "flat-bottom" cups, I wanted to use any cup in my cupboard
- I wanted the coffee to stay hot, not just warm
- I needed auto-off, since I surely would forget to turn it off
- Idiot-proof controls
This product's description seemed to check all the boxes, and it delivered! I've been using for several weeks and it's been perfect. It works with my regular ceramic coffee mugs, and on high setting, keeps my coffee pretty hot (130F). All my ceramic mugs are concave bottom - look at picture in my review - so that's why it only gets that hot on High. A flat-bottom cup may only need Medium setting since it would have more contact area for heat transfer.
The faux-wood trim makes it look sorta classy, and although it is large, it doesn't look absurd on my desk, and I'd rather it be bigger than my cup, rather than too small. And I imagine I could use it to keep soup or other food warm on my desk, since I also take forever to finish food when I do eat at my desk. The faux-wood trim does not get hot-to-touch, so it also prevents burns from accidental touch. The surface is, of course, very hot but no little kids or cats in our house, so that wasn't a concern for me.
I'm glad I went with this 36W option, even though some articles I read indicated this was overkill. As mentioned above, I imagine I need the higher wattage heating element because I use regular concave-bottom coffee mugs. I have it plugged into surge protector that powers my tower PC and 4 UHD 27" monitors, and I haven't tripped anything yet. 36W is even less than what a fast-charging laptop charger would pull, so this doesn't seem excessive for a workstation.
FOOD SAFETY WARNING: As a former research lab assistant that grew bacterial cultures as one of my duties, I'd like to remind people to keep in mind that the danger zone for bacterial growth is ~40F to 140F, especially with dairy creamers. To test temperatures, I used a ceramic concave-bottom mug (starbucks mug in picture) and a metallic flat-bottom mug (green mug in picture). Here are the liquid temperatures I measured for this warmer:
- Ceramic convex-bottom mug, Warmer on High: 130F
- Metallic flat-bottom mug, Warmer on High: 175F
- Metallic flat-bottom mug, Warmer on Med: 150F
As you can see, the concave-bottom makes a significant difference in heat transfer, and thus the temperature of the liquid. Use common sense on how long you leave your coffee on the warmer. Coffee at 130F is probably fine for a couple hours, but if you're gonna be leaving it all day, you'll want it to be at 140F+, so use a flat-bottom cup. The metallic one I have got real hot to the touch, including handle and lip of cup, even at Medium, so you'll probably want to use a ceramic one.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 7, 2024
★★★★★ 5
My favorite desk item
Color: Wood
I love my coffee but it must be hot-every sip! I'd get up at work so often to go reheat my coffee in the nuker & don'tlike the microwave AND a hater coworker even commented to me that she noticed "how much I get up from my desk" so I thought, they gotta be making coffee hot plates for desktops these days & boom, they do!! I like the wood finish, right my aesthetic alley. The plate has 3 settings; high, medium & low. Even has an auto shutoff after..idk how many hours so built in safety. I've even put my ceramic cup of soup on there to keep it warm while I work through lunch a couple times & it worked for my soup on the high setting. Coffee goes to medium when I first get in since it cools on the car ride over & then down to low once it's hot again. Will be getting one for the home office here soon.
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Reviewed in the United States on May 2, 2026
★★★★★ 5
Mug warmer
Color: Wood
This is a well made mug warmer, heats up quickly and convenient to use. The heat ratio is high making it easy to select the level of heat one wants to have to enjoy their coffee, tea, hot chocolate, etc. The only default I have with this product is how to turn on the warmer. It's convenient but if something is sitting next to the warmer, the warmer turns on too easily. I would recommend the manufacturer use some type of switch to turn on, adjust and turn off the warmer due to the chances of heating something up that was not intentional!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 26, 2026
★★★★★ 5
Simple and very useful
Color: White
Right out of the box it works just as expected, gets perfectly hot. Even with a small cup, my coffee typically cooks to quickly for my taste. Jumping up to give it a pop in the microwave gets old fast. Problem solved. For already hot coffee, the low is enough to keep it sippable. I'm pretty sure I could hear a can of soup from room temp on the high setting. I do hope it is doable because this is a perfect hot plate.
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Reviewed in the United States on April 22, 2026
★★★★★ 4
Works great but design flaw.
Color: Wood
Works great. 3 settings. The first is HOT. I usually use the middle or low setting and they keep my cup warm and drinkable. There is a flaw though with this device. The warming button is so easy to touch /come on that several times on my desk, it has come on without me realizing it from paper hitting it, a pen rolled against it or simply moving it over and it is on highest setting when it comes on so I have burned my fingers now twice. I just always double and triple check it isn’t on.
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Reviewed in the United States on February 14, 2026