TLDR: about 25 degrees Celsius difference between my laptop's stock fans and the highest setting on this BS2 Pro cooler (you need 27+Watt adapter for the max setting). It's very quiet, sits well on my lap, but I wish there was an easy method to replace the foam if it ever wears out. It works great so far, so I highly recommend trying it. AND I was cautious about using this store initially, but customer support is good, fixed the problem with my first order swiftly, and this product is working great so far.
So I'll throw the most important bit of info here at the beginning. I tested with The Talos Principle 2 at nearly max settings on 2560x1600 with no DLSS. This is an Unreal Engine 5 game and my computer is a Lenovo Legion 7i Pro with 13th Gen Intel(R) Core(TM) i9-13900HX and RTX 4090. I didn't measure the GPU temps because this computer already kept that hardware really cool regardless.
No laptop cooler/stock fans: Max CPU temps hit the thermal throttling limit of over 95 degrees Celsius. Average was low 80s Celsius.
BS2 Pro first/lowest fan setting (tldr between 8 and 10 degrees Celsius improvement): Max CPU temps were high 79s Celsius. Average was low 70s Celsius.
BS2 Pro second fan setting (tldr about 5 degrees Celsius improvement over first setting): Max CPU temps were low 70s Celsius. Average was mid 60s Celsius.
BS2 Pro third fan setting (tldr about another 5 degrees Celsius improvement over second setting): Max CPU temps were mid 60s Celsius. Average was low 60s Celsius.
BS2 Pro MAX fan setting (tldr about another 5 degrees Celsius improvement over third setting): Max CPU temps were around 60 degrees Celsius. Average was mid 50s Celsius.
So the BS2 Pro has 4 settings. You can have more control I think if you install Fydigi's software, but toggling between the settings manually was easy enough without it (you just press a button on the cooler).
The fourth setting requires using a charger/adapter with 27W or more, which are easy enough to get and not very expensive (i used an "Anker - PowerPort III 65W 3-Port Wall Charger").
Your laptop will sit on the foam, sealing the environment between your laptop's bottom vents and the cooler. The cooler also happens to lay comfortably on your lap if you're like me and don't use a table or desk.
It runs VERY quietly too. About the same noise level or a little quieter than my laptop's stock fans on full blast.
My only complaint is that the foam is stuck to the BS2 cooler, so replacing it might be a challenge. However, that's something that might happen in the distant future, and Flydigi and Gadgethyper already said they'd provide assistance if the foam eventually wears out.
I don't have much else to say about this. I've had it for about a month now and it's showing no signs of wear or age, but I'll update if anything strange happens. I highly recommend trying this out, because it gives a BIG difference in my computer's thermals.