When the potential relay on a hard-start kit fails with the contact stuck in a closed position, the motor-start capacitor remains in the circuit. This makes the AC compressor run with too much capacitance, causing damage and even potential failure. The CPT® Fuse Wire prevents this damage. When the relay becomes stuck in the close position, the fuse inside the wire disconnects within 3 seconds, cutting the motor-start capacitor off from the AC system. No damage, no mess, easy replacement.The only truly UNIVERSAL hard-start kit.Replacing 4 commonly used hard-star kits up to 5 tons.Up to 1 TON (108 – 130 MFD)1 – 2 TONS (189 – 227 MFD)2.5 – 3 TONS (233 – 280 MFD)3.5 – 5 TONS (270 – 324 MFD)