Folbe's popular 3” wire sheave trolling blocks is a perfect fit for the harsh demands of the marine environment. Made of marine grade Fiber-reinforced nylon that is virtually indestructible and paired with self-lubricating Oilite bushing system that creates a low friction, low wear surface that is virtually indestructible. Lab tested to 1500 lbs (not including swivel or chain). We have a safe working load limit of 400 lbs dead weight load.