Shield is an English company that has been manufacturing red dot sights for a long time.
https://www.shieldpsd.com/
The J-Point is one of their models, and they have manufactured similar sights marked for other retailers. It is a “miniature” red dot with a smaller footprint, both in width and length, than most competing red dot sights, like the Trij RMR, Vortex, Deltapoint, etc.
The Shield RMS (Reflex Mini Sight) is an advancement over the J-Point but with the same footprint. The first version looked similar to the J-Point but with open sides and better quality and features that made it cost over $100 more, about $400 retail when you could find them. I have one custom milled on my Shield 1.0.
The RMS 2 is waterproof and has some different improved features. It also has open sides that differentiate it from the J-Point. Still the same small footprint. And another $100 higher price tag at about $500 when you can find them at American retailers.
So what is S&W using? I have not handled one so these are just my opinions from the photos I see and the rather obvious lack of pride S&W is displaying by not telling anyone what the sight really is.
It’s a low end J-Point specially manufactured for S&W by Shield in England. There are no markings on it. That would be impossible for a good sight manufacturer to do without a special contract calling for it. I don’t know the features, but at a S&W price point of ~$285, it’s not one of Shield’s better sights.
The good news is the slide cut will fit the other better Shield models. The bad news is they are all red dots, and S&W Performance Center made the rather foolish (IMO) decision to put fiber optics on the milled slide with a yellow front light tube. So, when adding a Shield RDS you will see three red dots and a yellow dot in the sight window. Confetti sights are confusing, to say the least. The FO sights would be the first thing I would replace on the optics ready slide, and I would not buy the cheap “off brand” optic S&W is offering, at least not for personal defense. As an expensive toy, OK.
So what is S&W really offering? A poorly thought out handgun with whistles and bells that the whistle and bell buyers will buy because there are whistles and bells. The way it is set up it is not a serious self defense pistol, IMO.
The 4” tube is great; improved grip = great; improved trigger = wonderful; not screwing with the slide stop (like FS 2.0 versions) = a big plus; optic cut is the right one for this gun. Buy just those features and you will have a good gun to build into a great CC gun by adding better iron sights and a higher end optic.