This upright lead block with a 20mm sheave from Ronstan is typically used for halyards at the mast base. Lead blocks are a low-profile solution for leading halyards or other rig sail controls back to cleats or jammers. Ideal for high load applications. Manufactured with a wear-resistant Nylatron sheave – a lightweightself-lubricating polymer. This upright block is suitable for use with rope or wire. Features: High static and dynamic load capacity 316 Stainless Steel housing Light weight Cheek cutouts for easy bearing maintenence Fastening: 2 x 6mm (1/4″)- Not included SKUSheave DiameterMax Rope DiameterMax Working LoadBreaking LoadWeight RON-RF20171 20mm 6mm 250kg 550kg 18 grams