I did my homework on this 6 years ago, and my memory isn't perfect but here goes:
Purchased for travel to India where the air pollution at ground level is harmful. If taking a rickshaw ride across the city, the grey with minimal pink may draw a little less attention than the pure pink filters.
They are for people that have to work a little harder, and have a higher rate of respiration than the 2097's can sustain.
As far as welding goes, you need fume removal. It's good to have something extra. The filters with rigid plastic housings do not fit under my welding helmet. These might, but I have a different one that I use for welding - and that isn't very often - only for hobby use.
Not sure about today, but a few years ago the 3M site was not usable for information. The description for this product is awful in that it no longer states if it's for a pair of filters, or only a single one. I'll order because I need it for sanding but will be not be happy if a product I purchased in the past as a pair now only arrives as a single filter.

I am enrolled in a welding class at the local community college. On the 2nd class day we were stick welding 3 hours straight. At the end of the class I looked in the mirror, my face had a layer of soot, and I won't go into detail what came out of my nose. Simply put, smoke of any kind is not healthy. Especially welding smoke and fumes. Quite frankly I felt like a dog. I knew what the problem was. That evening I reasearched as much as possible on face masks and respirators. The 3m 2297 along with the 3m 6503QL Quick release respirator seemed to be the best combination. What a difference.....no hint of smoke or fumes when breathing through this respirator filter combo. You may not look as cool with a respirator on while welding, but I am pretty sure you will live longer for using it. Not to mention all the medical bills etc related to breathing problems. You don't have to breathe that stuff. This is some of the cheapest insurance you will ever purchase. No problems with the respirator/filter under my helmet.

"The filtration efficiency of selected NIOSH-approved particulate N95 and P100 filtering facepiece respirators (FFRs) and filter cartridges was investigated against the viable MS2 virus, a non-pathogenic bacteriophage, aerosolized from a liquid suspension. Tests were performed under two cyclic flow conditions (minute volumes of 85 and 135 L/min) and two constant flow rates (85 and 270 L/min). The mean penetrations of viable MS2 through the N95 and P100 FFRs/cartridges were typically less than 2 and 0.03%, respectively, under all flow conditions. All N95 and P100 FFR and cartridge models assessed in this study, therefore, met or exceeded their respective efficiency ratings of 95 and 99.97% against the viable MS2 test aerosol, even under the very high flow conditions. These NIOSH-approved FFRs and particulate respirators equipped with these cartridges can be anticipated to achieve expected levels of protection (consistent with their assigned protection factor) against airborne viral agents, provided that they are properly selected, fitted, worn, and maintained."

Gardner PD, Eshbaugh JP, Harpest SD, Richardson AW, Hofacre KC. Viable viral efficiency of N95 and P100 respirator filters at constant and cyclic flow. J Occup Environ Hyg. 2013;10(10):564"572. doi:10.1080/15459624.2013.818228

With that being stated, I'm putting my trust in NIOSH P100. Compared to the 2097 and 2297, the 2297 is indeed easier to breathe through.

From the beginning of year, when this crisis was rising, I've been using my stockpile of 2297, which was primarily used for Fiberglass Sanding, as a means to avoid airborne disease.

My first job, I'm a repairman for boats and surfboards, but it's my second job, Private Medical Transporter, where it's extremely useful when transporting gurney and wheelchair patients.

Favorite filter for ragweed allergy season. I can actually go to work and not get sick. Since I am severely allergic to ragweed, as my children say, you don't go to the doctor often, and you don't go to the emergency room at all. It worked great for going into my house after a house fire. I could smell the burnt items, but I did not develop a cough or anything. The mask cleans well and did not retain the burnt smell. I tossed the filters and I already have new filters for this fall. It is easier to breath with this filter system compared to a N95 mask, and you can replace the filters. I keep my mask in a plastic bag and usually just use one set for the entire three months without problem. I did lose one filter once, so I keep an extra set for back up. Holding your hand over the filter site did not work as well as the filter!
Now I just need a Darth Vader t shirt to wear when out in public......

Much easier breathing than the pinks, and lasts quite a long time even in very dirty demolition environments