This is the problem everyone mentioned, you are buying from someone who cannot speak English he cannot confirm what is supplied how would anyone know what you are gonna get.

In the main water cooled spindles have an inverter but that doesn't necessarily have to be the case.

I was thinking about taking of the fan in a standard router encasing it in a water cooled jacket to cool it and so cut down the noise.

Looking at the link you are gonna get an air cooled spindle of 300W and we already pointed out that that machine is too small for a water cooled spindle.

Phil