That kryptonite's decently tough for what it is but still pretty limited in usefulness, and not cheap. (the hexagonal chain is a bit of a trick for tests more than anything else, because it defeats brand new bolt cropper blades which is what testers use, but doesn't make any real difference with a slightly worn blade as those will grip)
If you want a relatively portable chain, you might as well get an inexpensive one as none of them offer particularily good protection. But it makes little sense for pushbikes, you want D locks for portability, gigantic chains for security.