I wouldn’t really call the Nest Protect an elegant device since for me, it looked more like a wireless speaker, but there is no doubt that it did take a step into the right direction when it came to the aesthetic value of smoke detectors. The Onelink took inspiration and adopted a similar design, but the cheaper First Alert 2 in 1 Z Wave remained humble, featuring an octagonal rugged plastic case, lacking the flashy circular LED light, but still being equipped with everything one would expect from a smoke and CO alarm. So, on the front of the device, there is a fairly large Test/Silence Weekly button, a Power/Smoke Alarm LED and a CO Alarm LED light. On the lateral side, towards the front, there is a sliding compartment where you can enter or replace the batteries simple AA. All around the case and on the front, there are lots of cut out areas to allow a proper air ventilation and for the smoke to enter the device and trigger the alarms. If we take into account the backplate, the First Alert 2 in 1 Z Wave is thicker than your average smoke detectors, measuring 5. 0 x 2. 0 x 5. 0 inches but it’s fairly lightweight, weighing only 1. 0lb. This particular model does not come as a hard wired detector, the only way to power it remains through the use of batteries and the only smoke/CO detectors from First Alert that can be connected to the home’s power source are the 120V AC Smoke and Carbon Monoxide alarm and the already mentioned OneLink detector.