Q-BI58 is a recommended lead free soldering alternative for heat sensitive components that require a low melting point. The low melting point 138E degrees C prevents thermal degradation of heat sensitive components. Qualitek Sn42/Bi58 alloy meets or exceeds J-STD-006 requirements and all other relevant international standards. Sn42/Bi58 is sold per 500 gram box and available in a wide variety of Diameters. Most popular are as listed: Q-BI58 - Sn42/Bi58 Solid Solder Wire, .048?plusmn; dia. 500 gram box Q-BI58 C Sn42/Bi58 Solid Solder Wire, .032?plusmn; dia. 500 gram box Q-BI58 C Sn42/Bi58 Solid Solder Wire, .040?plusmn; dia. 500 gram box