It's called a bumpsteer kit but it has minimal impact on your bump steer! Besides, it depends how much bump steer you start with. Bump steer is not a huge issue with our cars unless you over lower them and if you did then this wouldn't help as the change is too small.
It is a rose jointed track rod end which doesn't sound very exciting but it is brilliant for improving steering feel and accuracy.
The ball joint at the end of your steering has a little slack that gets's taken up every time you move the steering wheel. Rose jointed track rod ends don't have this. This description isn't going to make people reach for their wallets so marketing reach for bumpsteer mumbo jumbo to sell a few more
Cynicism aside, they are good, the problem used to be that they wore out too quickly, almost every year. So many moons ago Steve found the bearing company in the link above who supply a much higher grade of bearing than the type you normally get from aftermarket tuners. They also sell the boots that you can pack with grease to keep them safe from dust and corrosion. End result is mine have done around 25,000 miles of daily driving over 5 years with no issues.
You don't need coilovers to make this work but you don't want worn bushes, dampers and soft springs as the chassis will be unresponsive anyway.