No, it's plastic, made by Enduramaxx. The pump is stainless steel.Some more questions if you don't mind, having read all of this again:
1. So you tank is stainless steel and not plastic?
2. In your first post you said that this will be cheaper than a dedicated rainwater harvesting tank. What makes this any different from the dedicated one?
3. If it stainless steel, I would have thought that it would cost more than plastic?
4. The steps you describe in your last post for your setup seems quite complicated for an ordinary person, are you just a good DIY'er or a plumber who can do all this stuff easily?
5. How did you drill through and cut holes in a stainless steel tank?
6. Given that plastic tanks would probably have better sound insulation naturally, do you hear the pinging sound of new water from the gutter hitting the tank or the water inside when partially empty?
Rainwater harvesting tanks have to go through approval processes to allow them to store water for use inside a building, flushing toilets, running washing machines etc. If you're just using it for watering the garden, you don't need an approved tank.
All very easy to do once you've got the right bits together.
A standard holesaw of the right diameter will cut the holes.
There's no audible noise from inside, unless the pump has been left on then there's a faint hum