Southwire 64169622 5 Conductor 18/5 Thermostat Wire, 18-Gauge Solid Copper Class 2 Power-Limited Circuit Cable, 50-Feet, Brown by Southwire

Lo que necesitaba para conectar mi calefaccion a un termostato inteligente.

It's fine. It's exactly what it says it is- 18 AWG solid copper wire. Solid wire is less flexible than stranded wire, so you can ignore any reviews complaining about thickness or stiffness.

Great cable for wiring up your nest, echobee, etc. Stiff and somewhat difficult to pull but great once it's done. Better than using cat6.

Product came as a spool (50 ft 18/5), appears correct, new, Southwire brand. Wire colors are red/blue/white/yellow/green, brown jacket. Has that handy "thread" also, that allows you to easily split the jacket open. Measured thickness for solid core looks like 18AWG. Internal colored insulation is thin, but presumeably adequate for the 150V rating. The 4th image shows a piece of the blue wire compared to an older (black) thermostat wire (from an 18/2 cable) that had a thicker insulation layer.

Good quality thermostat wire. I upgraded my thermostat from a 'dumb' thermostat to a wifi programmable one, and needed a power wire (the 5th wire). I was able to pull the new wire in the wall by hooking the new wire to the old wire and pulling it up through the wall. It made replacing the wire very easy.