So how are they any different from regular response, Flowable silicone, Rtv silicone, and how are they better?

K-pads are really good, i mean REALLY good. It lasts so long and gives tight binds. If you are using YYFs, SPYYs, or C3s, K-pads are the best choice
K-pads are machined pad, Flowable and RTV silicone is self-installed pad. i haven’t use flowable silicone before, but Flow Groove Pads (which is made from Flowable silicone), is the best response i’ve ever used

They are 19 mm pads, they fit a lot of brands of yoyos. YYF, SPYY, C3 and a lot more. That particular size of pad is pretty common and made by a variety of different companies. However, the official “k-pad” is made by Turning point. Though Central bearing company (YYF pretty much) makes the same size pad as well. In my experience they all work about the same. Pretty good.
Nothing beats flowable silicone though in my opinion, its cheap, easy to install, and lasts forever. You can get a tube for about five bucks and that will last at least 3-4 months depending on how much you waste, and how much you yoyo. You can find tutorials on how to silicone your yoyos at the top of this section.
Hope this helped!