This solder flux is very low viscosity so it easily and quickly flows in and around all surfaces requiring fluxing in preparation for soldering. It's excellent fluxing properties product shiny, smooth solder joints of the highest quality. We have tested many different solder fluxes and found this product to produce the most uniform results with the major benefit of leaving NO residue, requiring NO cleanup. It is packaged in a handy 1/2 oz. dispensing bottle with a Luer-Lock® Cap and includes a mating Luer-Lock® Stopper, and a 27 Gauge (0.016" OD) blunt needle with a Luer-Lock® base. The needle is 0.008" inside diameter to produce very tiny droplets of flux for soldering small, delicate parts.