Yuguang's Brazing Rings are the cleanest and brightest, free of oxide and surface impurities. Yuguang's alloys are pure and shiny, and that cleanliness runs all the way through the rod. What a huge difference purity makes in the integrity of your brazed joint. Leaks are caused by oxide and impurities that enter the joint in the molten metal of an impure brazing alloy and impede the brazing alloy flow. Wherever there iscontamination, the alloy flows around it, leaving pinholes in the joint. Thesepinholes are tiny doors which allow refrigerant gas to leak out. Features: 1) Popular Standard: BCuP-2, BCuP-6, BCuP-3, BCuP-4, BCuP-15 etc 2) Popular Size: 1.6 x 6.9mm, 1.6 x 7.8mm, 1.6 x 9.4mm, 1.8 x 9.4mm etc 3) Tolerance of wire diameter: +/-0.02mm 4) Tolerance of inside diameter: +/-0.05mm 5) Max gap: 0.3 mm 6) Helix: 0.15mm7) For brazing copper parts in air-conditioners, freezers, refrigerators and motors.