Barton Size 1 Ball Bearing Block Stand Up A strong, lightweight block ideal for use on dinghies and dayboats or as lead blocks on larger craft. Sheave size: 30mm x 12mm (1 3/16 x 15/32inch) Max rope diameter: 8mm (5/16inch) SWL: 350kg (771lbs) Break load: 700Kg (1543 lbs) Length: 79mm Weight: 60g