SKU: 88075100913

DAHUA HY-SA21A-W2(868) Wireless Smoke Alarm

Sale price$450000.00 Regular price$500000.00
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Description

DAHUA HY-SA21A-W2(868) Wireless Smoke AlarmHY SA21A W2(868) Wireless Smoke Alarm > Split spectrum sensor technology > Test and silence features in one single button > Loud sound output over 85 dB(A) at 3 meters > Low quiescent current consumption > Surface mount device (SMD) circuit board design > Low battery warning signal Product Data Working Principle Collection Type Smoke Sampling Period 10 s Sensor Type Photoelectric Alarm Alarm Type Smoke alarm, fault alarm, low battery warning Alarm

HY-SA21A-W2(868)

Wireless Smoke Alarm

> Split-spectrum sensor technology
> Test and silence features in one single button
> Loud sound output over 85 dB(A) at 3 meters
> Low quiescent current consumption
> Surface-mount device (SMD) circuit board design
> Low battery warning signal



Product Data

Working Principle

Collection Type

Smoke

Sampling Period

10 s

Sensor Type

Photoelectric

Alarm

Alarm Type

Smoke alarm, fault alarm, low battery warning

Alarm Volume

85dB–90dB(A) at 3 m (9.84 ft)

Alarm Mode

Visual and audible alarm

Silence Function

Yes

Silence Duration

About 12 min

Alarm Response Threshold

0.2 dB/m - 0.3 dB/m

Basic Parameters

Indicator Light

Red and green LED indicator

Led Instructions

Standby: Green indicator flashes once per minute
Alarm: Red indicator flashes once per second
Fault: Red indicator flashes once per minute

Low battery warning: Red indicator flashes once per minute

Coverage Area

When the height of the space is less than 8 m (3.28 ft), the protection area of a device is 20 m2–40 m2

Power Supply

Battery Life

3 year

Operating Voltage

3V CR123A lithium battery (replaceable)

Operating Current

Monitoring current: ≤ 35uA
Alarm current: ≤ 35mA

Operating Ambient

Operating Environment

Indoor

Operating Temperature

-10°C to +55°C (+14°F to +131°F)

Operating Humidity

≤ 95% RH (non condensing)

Appearance

Color

White

Casing

ABS

Dimensions

φ98mm × H43.1mm (φ3.85" × H1.70")

Weight

140 g (0.30 lb)

Installation

Ceiling Mount

Certifications

Certifications

TÜV and CE listed

Compliance Standard

EN 14604:2005+AC:2008

Wireless

Carrier Frequency

868 MHz–868.3 MHz

Communication Distance

Up to 1000 m (3280.84 ft) in an open space

Communication Mechanism

Two-way

Frequency Hopping

Yes

Encryption Mode

AES128

Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. 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
SKU: 88075100913

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4.3 ★★★★★
Based on 19 reviews
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Product Reviews
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Verified Purchase
kkl
Natrona Heights, US
★★★★★ 5
Very good product
Size: Medium, Color: (001) Black / Black / Pitch Gray
I purchased these to wear inside lowcut slip on casual shoes, I don't particularly like to not wear socks in my shoes for hygienic reasons. Prior to purchasing these socks, all I could find were those made of very light beige hosiery type material , and my slip on shoes would slide around a bit. These are light weight and breathable athletic type material, with a very good gripper strip at the heel. One pair of my slip on casual shoes have a particularly lower cut in the toe area, but the shoe is black and I chose the black color and though I see a hint of the sock there, it matches and does not detract from the look of the casual solid black shoe
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 15, 2026
A
Verified Purchase
Anna Wylda
Birmingham, US
★★★★★ 5
They stay out! No more sock wads!
Size: Medium, Color: (100) White / White / Mod Gray
Best no show socks ever made!!!!! I've been struggling for 2 years to find ones that actually stay on your foot, even other national brands, and I just became content wearing my sneakers without socks. They ALWAYS slid down into my show & I ended up walking on a wad of sock until I could fix it...or usually just took them off after a couple of tries. Enter Under Armor!!! They a mid weight, but not very thick & still breathable. They work too by actually staying on your foot! Not once have they slid down into my show!! Very comfortable but they could be a little more affordable.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on August 1, 2025
R
Verified Purchase
Rebekah
Pawtucket, US
★★★★★ 5
Love!
Size: Large, Color: (100) White / White / Mod Gray
Ive tried so many no show socks but I love these. This is the 3rd set I've bought. They never slip off and the material is thin and breathable. Perfect for working out.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on March 2, 2026
B
Verified Purchase
Becky
Chelsea, US
★★★★★ 5
True no-show socks that don’t slide down!
Size: Medium, Color: (100) White / White / Mod Gray, Size: Medium, Color: (100) White / White / Mod Gray
This is the first pair of no-show socks I’ve tried that actually don’t slide down into my shoes. Trust me… I have tried lots of different pairs and this is the one! They fit perfectly. They’re not too thick and they’re obviously durable because I wash them after each wear, so daily.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on March 21, 2026
R
Verified Purchase
Raquel Hall
New York, US
★★★★★ 4
Great fit but expensive
Size: Medium, Color: (252) Blush Beige / White / Castlerock
These are really great socks. I love them, but they are definitely pricey.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on March 30, 2026

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