Block, ball raced, micro - 4 mm sheave. SAILSetc design and manufacture. A beautifully simple design of block for lines up to 0.4 mm diameter. Suitable for use with the main winch loop system on the footy and smaller boats. Useful for other applications on miniature craft. Intended to be used with 5 or 10 kg BS Dyneema. Designed to be used suspended on 10 to 20 kg BS Dyneema line. When suspending the block on a line, it is important that the line passes through both holes in the block in the way shown in the thumbnail sketches above.