Brake flush kits on a drum set up will not prolong the life of the brakes all that much, maybe a year. If the trailer is used with any regularity you will get a maximum of 3 years before the brakes will need service. BTW you need to flush right after launching and right after retrieving to get any results. Most people only flush at the end of the day. The trailer sits with salt water in the brakes all day while you are fishing. Flushing at home after use also is bad, brakes never dry out. Flush at ramp then drive home, the heat from use will dry them off.