A flare tool is a specialized plumbing tool used to widen the end of a copper refrigerant pipe into a 45-degree bell shape. This flare allows the copper to be compressed by a flare nut against a fitting, creating a high-pressure, leak-proof seal. Creating a perfect flare is the most critical skill for a successful diy-1 mini-split installation. If a flare is uneven or has burrs, it will eventually leak refrigerant, leading to system failure. We recommend using a high-quality eccentric flaring tool for all our one zone wall mount projects. Proper flaring ensures your multi-zone wall mounts remain operational for many years without needing a recharge.