For one reason or another, you may run out of one component of PropSpeed's Foul Release System Kit.
If you need more of the Etching Primer, this is what you want to buy.
PropSpeed Etching Primer is one of the best underwater etching primers on the market. It is known for its tenacious adhesion and corrosion resistance.
Only use on non-ferrous metals - brass, bronze, aluminum, zinc
Contains 240 ml Etching Primer Base, and 60 ml Etching Primer Hardener.
This is the amount supplied in the 500 ml PropSpeed Kit (PRS 783A).
Note - For best adhesion, it is highly recommended that you pre-treat the metal surface with PropPrep Metal Wash & Surface Conditioner prior to applying the Etching Primer; see Related Products, below.