Ball bearing blocks deliver sensitivity to hand held loads. This 40mm single stand up block is a workhorse and can be used for a wide range of application. Great for mainsheet systems where the sheet is controlled from a wide range of angles. The smaller sheaves are compatible with up to 3/8"Sailors can detect changes in wind intensity and direction by feel. Hand held loads of the main and headsail, spinnaker and other control lines communicate valuable information to the crew. Lewmar Control Blocks are designed to keep these lines of communication open. By using ball bearings, Control Blocks assure sailors that small signals wont be lost in unnecessary drag or friction. These light weight blocks are ideal for control lines and other hand-held loads. Long fiber technology used in the construction of the composite cheeks adds strength while keeping the overall weight down. An open design is used in the cheeks to reduce maintenance: saltwater and sand can be easily flushed from the block and the bearings lubricated. The sheaves use the same long fiber technology for strength and feature a metal insert for the bearing surface. This addition improves performance and longevity. Line size compatibility and safe working loads are indicated on the sheave of each block to avoid failures caused by overloading the block. Get the messages your boat and sails are sending you loud and clear with help of ball bearings and Lewmar Control blocks. Key Features Light weight blocks that are ideal for hand held controls Ball bearings deliver smooth and long lasting performance Long fiber technology is used in composite cheeks to add strength while reducing weight Composite sheave with metal bearing surface Sheaves are marked with safe working loads and line compatibility Compatible with up to 3/8" line Ideal for medium dynamic loads Mainsheet systems on dinghies and smaller keelboats Halyard turning blocks Control lines operated from a wide range of angles Selection GuideSheave DiameterLine Range30mm5/16" (8mm)40mm3/8" (10mm)