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RF72100 – Ronstan Series 75 Ultimate Ratchet Single Block, Manual, Swivel Shackle Head

$314.72 incl GST



  • Unrivalled 20:1 holding power
  • Dual sided On-Off switch
  • Ability to operate On/Off switch under load
  • Low friction ball bearing system
  • Lightweight
  • Cheek cut-outs for easy bearing maintenance

The patented extruded hole design, in conjunction with the groove profile of the sheave, provides a more powerful grip than conventional designs – up to 20:1 holding power. Unrivalled low weight is achieved by the use of a Torlon® ratchet pawl, high grade machined alloy sheave and black Acetal hubs and bearings. On-Off switching knob is fitted to both sides of the swivel blocks (one can be removed if desired). Ratchet blocks can be disassembled for sheave replacement with RF62000.


  • Mainsheet on powerful dinghies and skiffs
  • Series 60 mainsheet systems on sportsboats using RF7 mainsheet swivel units
  • Control line applications on larger yachts
  • Spinnaker sheets on sportsboats and small keel boats (lateral lead blocks)


Product NoSheave Dia mm (in)Max Rope Dia mm (in)Max Working Load kg (lb)Break Load kg (lb)Weight g (oz)Pin Dia mm (in)Fasteners mm (in)
RF7210075 (3)12 (1/2)420 (930)2000 (4410)162 (5.7)7 (9/32)-
RF7217475 (3)12 (1/2)420 (930)1370 (3020)270 (9.5)-6 (1/4)
RF7217575 (3)12 (1/2)420 (930)1370 (3020)405 (14.3)-6 (1/4)

Additional information

Weight .162 kg