DPSS 808nm laser..?
OD1 reduces power by a factor of 10, OD2 reduces by a factor of 100, OD3 reduces by a factor of 1,000, and so on. You want to have at most 5mW going through the goggles, so you want to get at least OD4.
I HIGHLY recommend indirect viewing when using very high power diodes. Use a video camera, they work great. Do not look at the laser spot without the camera, expecially if you will be using it to pump crystals. A reflection from an uncoated portion of the crystal or from its surrounding metal mounts will be very dangerous.
At LaserGlow's site, their OD5 Glasses have the wavelength and up to 500W. Others say up to 500mW, so I'm not sure if this is a typo, or the different wavelengths have different ratings or something.
I don't see any typos on the Laserglow goggle page..? For the first pair it says up to 500mW because it is OD2, second pair says over 500mW because it is OD7.
Those are only OD3. If that laser somehow gets through the goggles, then the reduced beam will be 40mW. Which can cause damage to the eye, particularily because you can barely see 808nm.
As I've mentioned before, the OD rating is pretty irrelevant in this case. Generally an OD rating is used if you want to look at the spot in comfort for focusing. IT DOES NOT TELL YOU HOW MUCH ENERGY THE GLASSES CAN WITHSTAND, so focusing (pun) on OD is a grave error.
What you want here, is PROTECTION from a nearly invisible high-power beam. For that (and with 40W), you'll most likely need glasses that have a reflective coating for the wavelength in question, which are likely to cost a bundle.
So, forget all answers that mention "OD". Check this thread for someone (AndrewGW) who may give you more relevant info.