Hi there! I’m looking for some specs on the 40w laser, specifically the Wavelength Range and Optical Density. I am looking to purchase safety goggles and want to be sure I’m getting appropriate ones. Thanks!
Note: I am aware Snapmaker sells safety goggles as well but I would like to look around first before making a decision. 
According to the shop page it is 450-460 nm wavelength:
The goggles that Snapmaker sells are OD6+ in that regime:
Which I personally would deem good enough for 40W laser. That said, the Snapmaker type leave gaps between your skin and the edge of the goggles, so there’s still a remote chance of a stray beam to hit you - me personally thinks that the chance is very remote, but if you’re the very careful type, I’d recommend goggles with a rubber lip that seals your eyes completely.
Thanks, @Hauke! I saw the Snapmaker goggles had OD6+ but just wanted to be sure it would be sufficient, as the product page only mentions the 1.6W and 10W lasers. Call me paranoid but I kind of like the idea of not frying my eyeballs. 
The general logic behind the OD rating is: The number behind OD tells you how many orders of magnitude the laser is reduced. So, with 40W you have:
OD1 → 1 order of magnitude less → 4W
OD2 → 2 orders of magnitude → 0.4W
…
OD6 → 6 orders of magnitude → 0.04 mW
AFAIK 1 mW laser power is considered safe even as a direct hit, as the eye lid reflex will be fast enough to close before permanent damage is done. I think if you want to be really scientifically correct, you’d need to take the beam diameter into account, but for the Snapmaker lasers the above should be OK. here’s a bit reading on that:
Important: I’m not an expert, so make sure to get independent information you trust!
That’s not paranoid, that’s common sense!
where can I download this test file?