Nylatron Sheave Box – Single Upright Lead Block
Lead blocks are a low profile solution for leading halyards or other rig sail controls back to cleats or jammers.When mounted in an inverted position, are frequently used as upright leads.
Features:
The external tabs can be formed to fit the spar profile before fastening
Applications:
Typically used in dinghy spars for control lines such as outhauls
Materials:
- Nylatron® sheave
- Grade 316 stainless steel load housing
Specifications:
Sheave Ø:t22mm(7/8″)
Max. Rope Ø:t3mm(1/8″)
Max. Cable Ø:t3mm(1/8″)
Fastener Ø:t5mm(3/16″)
M.W.L.:t160kg(350lbs)
B. L.:t350kg(700lbs)
Weight:t30g(1.1oz)

![Ronstan Series 20 Ball Bearing Block - Swivel Hook Head [RF20180]](https://www.yachtseatworks.com/wp-content/uploads/2026/10/ronstan-series-20-ball-bearing-block-swivel-hook-head-rf20180.webp)
![Ronstan Race Sheave - Acetal Solid Bearing - 28mm (1-1/8") OD [RF128]](https://www.yachtseatworks.com/wp-content/uploads/2026/10/ronstan-race-sheave-acetal-solid-bearing-28mm-1-1-8-od-rf128.webp)
![Ronstan Series 20 Ball Bearing Block - Double - Becket - 2-Axis Shackle Head [RF20212]](https://www.yachtseatworks.com/wp-content/uploads/2026/10/ronstan-series-20-ball-bearing-block-double-becket-2-axis-shackle-head-rf20212.webp)
![Ronstan Wire Block - Ferrule Top w/Removable Nylontron Sheave - 45mm (1-34/") Sheave Diameter [RF104]](https://www.yachtseatworks.com/wp-content/uploads/2026/10/ronstan-wire-block-ferrule-top-w-removable-nylontron-sheave-45mm-1-34-sheave-dia.webp)
![Ronstan Series 20 Ball Bearing Block - Single - Cheek Rivet Mount [RF20151A]](https://www.yachtseatworks.com/wp-content/uploads/2026/10/ronstan-series-20-ball-bearing-block-single-cheek-rivet-mount-rf20151a.webp)
![Ronstan Race Sheave - Acetal Ball Bearing - 28mm (1-1/8") OD [RF1020]](https://www.yachtseatworks.com/wp-content/uploads/2026/10/ronstan-race-sheave-acetal-ball-bearing-28mm-1-1-8-od-rf1020.webp)
![Ronstan Dinghy Wire Block - Ferrule Top w/Removable Sheave - 25mm (1") Sheave Diameter [RF468]](https://www.yachtseatworks.com/wp-content/uploads/2026/10/ronstan-dinghy-wire-block-ferrule-top-w-removable-sheave-25mm-1-sheave-diameter-.webp)
![Ronstan Race Sheave - Acetal Solid Bearing - 50mm (1-15/16") OD [RF1759]](https://www.yachtseatworks.com/wp-content/uploads/2026/10/ronstan-race-sheave-acetal-solid-bearing-50mm-1-15-16-od-rf1759.webp)