Series 50 High Load Block – Single – Universal Head
Ideal for high load applications. Wear resistant sheave material, in lightweight, self lubricating polymer, is suitable for use with rope or wire.Captive Lock universal head can be fixed in either of two planes, or free to swivel as required.
Features:
- Exceptionally high working loads
- Lightweight
- Cheek cut-outs for easy bearing maintenance
- Suitable for both rope or wire
- Captive Lock universal head
- Slotted pin shackle eliminates fouled lines
Applications:
- Mainsheet
- Spinnaker sheets
- Halyards and other primary applications on boats up to 10M(33′)
Materials:
- Nylatron® sheave
- Grade 316 stainless steel load strap and head fitting
- Impact and U.V. resistant, fiber reinforced Nylon cheeks
Specifications:
Sheave Ø:t50mm(2″)
Max. Rope Ø: 12mm(1/2″)
Max. Cable Ø:5mm(3/16″)
Max. Pin Ø: 5mm(3/16″)
M.W.L.:t800kg(1,760lbs)
B. L.:t1,500kg(3,310lbs)
Weight:t117g(4.1oz)

![Ronstan Series 30 Fiddle Block - Narrow w/Tube Rivet HeadV-Jam Cleat [RF187]](https://www.yachtseatworks.com/wp-content/uploads/2026/10/ronstan-series-30-fiddle-block-narrow-w-tube-rivet-headv-jam-cleat-rf187.webp)
![Ronstan Wire Block w/Removable Clevis Pin Head - Nylatron Sheave - 25mm (1") Sheave Diameter [RF418C]](https://www.yachtseatworks.com/wp-content/uploads/2026/10/ronstan-wire-block-w-removable-clevis-pin-head-nylatron-sheave-25mm-1-sheave-dia.webp)
![Ronstan Series 20 ball Bearing Block - Triple - 2-Axis Shackle head [RF20302]](https://www.yachtseatworks.com/wp-content/uploads/2026/10/ronstan-series-20-ball-bearing-block-triple-2-axis-shackle-head-rf20302.webp)
![Ronstan Series 40 AP Sheave - Acetal Solid Bearing - 40mm (1-9/16")OD [RF41000]](https://www.yachtseatworks.com/wp-content/uploads/2026/10/ronstan-series-40-ap-sheave-acetal-solid-bearing-40mm-1-9-16-od-rf41000.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 Series 20 Ball Bearing Block - Single - Exit Cover Plate [RF20711]](https://www.yachtseatworks.com/wp-content/uploads/2026/10/ronstan-series-20-ball-bearing-block-single-exit-cover-plate-rf20711.webp)
![Ronstan Race Sheave - Rope/Wire - Nylatron - 25mm (1") OD [RF131]](https://www.yachtseatworks.com/wp-content/uploads/2026/10/ronstan-race-sheave-rope-wire-nylatron-25mm-1-od-rf131.webp)