A basin wrench is a small, specialized tool - much like a pair of snap ring pliers, used by plumbers to reach awkwardly sited nuts, which are found underneath basins and faucets. In short - they're plumbing tools and without them, sink and faucet assembly would be impossible. The design is unique to the task that they perform - long handled with a spring loaded swivel mount jaw.
The serrated jaws clamp onto the nuts and allow plumbers to loosen or tighten them. The same method is applied whether using them for faucet or basin-located nuts, though to switch between a sink and the faucets basin wrenches have to first switch through 90º.
The five best basin wrenches are featured below. They're all on the best seller list, deliver on both quality and value for money and possess highly positive ratings and feedback from satisfied purchasers.