500g high purity Rosin 
A flux with activators added to facilitate soldering; it is almost as active as soldering paste.

Very good flux when soldering with tin-lead alloy
may also be used for horsehair strings to increase the roughness and thus improve string adhesion
also as quality improving printing ink binder

Please Note :  It may come in sealable  plastic bags  and not in the same one as on the picture  

Properties: 

Rosin occurs as a hard, dry substance, brittle and friable, with a faint piny odor. It is typical a glassy solid, though some rosins will form crystals, especially when brought into solution. It is semi-transparent and varies in color from yellow to black. The practical melting point varies with different specimens, others melting at 100 ° C to 120 ° C. It is very flammable, burning with a smoky flame, it should be taken when melting it. It is soluble in alcohol, ether, benzene and chloroform.