Fernox F4 express leak sealer seeks out and seals most leaks and weeps in sealed systems without causing blockages or pump seizure saving time and money on draining down and unnecessary repairs. It can be quickly and conveniently added via a radiator adaptor or the filling loop supplied.

Combats emergency leaks and system pressure loss
Simple to use with no mess
100% recyclable can
400ml can
Non-toxic, environmentally friendly formulation