Welcome to the world, Nest Protect. Perhaps you will vanquish the ear melting, banshee cry of the over-excited smoke detectors installed in every home we've ever cooked in. Let's see what you're packing:

Available with 6 AA Energizer Ultimate Lithium batteries or Wired for 120 V

Wi-Fi connectivity and wireless mesh networking with other Nest units

Photoelectric smoke sensor and carbon monoxide sensor

Heat and humidity sensors

Three activity sensors

Ambient light sensor

The Nest Protect comes with a choice of power supply: battery or 120 V powered model.

Our battery powered detector claims its six AA Energizer Ultimate Lithium batteries have juice for "multi-year operation."

First stop: pop the top off the Nest button, the combination input switch and multi-colored sweeping light.

An ambient light sensor sits in the center of the button, with lenses in the translucent cover to increase its viewing angle.

A ring of RGB LEDs surround the sensor to make up the Protect's indicator glow:

White for the automatic night light

Reassuring green to indicate all's clear

Yellow for an early warning

Red for a get-out-of-town emergency

We pull out the impressive-for-a-smoke-detector main board, and the optical smoke detector is front and center, safely under its baffled shield.

As smoke enters the baffled chamber above the sensor, infrared light from the LED is scattered and reflected down into the photodiode, triggering the alarm. This sort of arrangement is standard practice for smoke detectors.

But applying the Nest Labs touch means adding all sorts of extra features for handling the alarm, like sending a notification to your smartphone that your house is on fire. Neat.

A little further into the device, and we find the CO detector, disguised as a capacitor in a tiny metal barn.

The Figaro TGS5342 electrochemical carbon monoxide detector works like a little fuel cell—the presence of carbon monoxide drives a chemical reaction that generates current proportional to the CO concentration in the air.

The detector's measuring circuitry is on the reverse side of the main board, encased in some clear adhesive—likely to protect it against shock and the atmosphere.

If a fire or CO leak is detected, an 85 dB horn raises the alarm while a separate speaker tells you to exit the building in the talking-bomb-countdown-timer voice.

Straight and angled motion sensors catch your waving arm when you want to silence a false alarm from cooking smoke or a steamy shower.

Down now to the heart of the brain (Just ponder that metaphor for a moment. Done? Wonderful, let’s move on). A quick look at the noteworthy integrated circuits running the Nest Protect:

Freescale SCK60DN512VLL10 custom Kinetis K60 low-power 100 MHz MCU

Silicon Labs EM357 Ember Zigbee SoC

Freescale SCKL16Z128V custom Kinetis KL1x general purpose MCU

Texas Instruments LM324A quadruple op-amp

Murata Type ZX 2.4 GHz Wi-Fi 802.11b/g/n module (with Broadcom BCM43362 chipset)

Texas Instruments TPS62737 Step-Down Buck Converter

The Nest Protect is straight-forward and easy to disassemble. Common screw types, user-accessible batteries, and a simple design make it a very solid, repairable product.

That said, we won't be assigning a repairability score, considering you probably shouldn't do anything more than replace the batteries in your Nest Protect.