The 24-6337-9727 is solder wire with Rosin Flux. Kester 285 Mildly Activated Rosin Flux is classified as Type ROL0 flux under IPC J-STD-004. This flux was formerly classified as Type RMA per QQ-S-571. 285 consists of high quality, purified rosin to which a synergistic combination of activating agents has been incorporated. The fluxing ability of 285 is much greater than ordinary mildly activated rosin fluxes and is comparable to fully activated rosin fluxes. 285 has been developed for use in the electronic industry where difficult assemblies are to be soldered, but process requirements stipulate use of a mildly activated rosin flux.