The Weller electronic solder EL99/1-25 with 1 mm diameter on a 25 g spool, lead-free solder. It is suitable for all soldering work in electrical engineering, miniature technology and on printed circuits. S-Sn99Cu1, DIN EN 29453 (Sn99.3Cu0.7). 2.2% flux according to DIN EN 29454, 1.1.2.B (EN 6190-ROM1) This accessory is compatible with the Ryobi RSI18 & R18SOI Soldering Irons and the RSI4-120G Soldering Pen in addition to other brands of soldering iron.