Folbe's popular 5” rope 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 2200 lbs (not including chain). We have a safe working load limit of 700 lbs dead weight load.