For anyone working with Blum TANDEM drawer slides, these locking devices are an absolute must-have! Each package contains 2 pairs (that's 4 total pieces - left and right for two sets of slides) that securely lock your overlay drawers in place. If you've ever used Blum's TANDEM system before, you know how incredibly smooth and reliable these runners are - they're pretty much the gold standard in drawer slide technology. These locking devices are what make the whole system work perfectly, ensuring your drawers stay securely mounted and operate with that buttery-smooth motion Blum is famous for. Installation is straightforward if you're familiar with cabinet hardware, and once they're in place, you'll appreciate how securely they hold even heavily loaded drawers. Whether you're a professional cabinet installer or a serious DIY enthusiast, having these on hand makes the installation process so much smoother. They're designed specifically to work with Blum's premium undermount slides (sold separately), so if you're building or upgrading cabinets with Blum hardware, don't forget to grab these locking devices. Seriously, trying to install TANDEM slides without these is like trying to drive a car without wheels - they're that essential to making the system work properly!