If you have a cheap bike with cheap blocky chunky fugly nonstop brakes and pads getting these shiny aluminum Yokozuna cartridge brake holders and pads is a simple and smart way to greatly improve the braking (the special Salmon brake pad compound is considered by many near and far to be the best for every condition).  It's easy to put in new pads (they work with Shimano slip-in pads such as these Koolstop inserts); just unscrew the tiny 2.5mm allen bolt on the back and pop out and pop in pads. Bonus that they look so pretty.

Not quite as slick as the Koolstop cartridge shoes since the Yoko's lack the Kool's ball socket toe-in feature and do not include a spare set of inserts But the Yoko's do have itty bitty bumpers on the wheel guides to prevent rim scrapage and scratching when the pads are close to being all worn out.