ISC Spring Block - 3/4" Medium



BREAKING STRENGTH150 kN (33,721.3 lb)

The ISC medium arborist block is a great tree rigging block for professional use. This block is built for serious use with practical features that set it above other tree rigging blocks.

The upper sheave is over-sized so that it can accept up to 1" tree rigging slings. The block is secured with a spring-lock. To open, the user simply pushes the pin in, twists, and the side plates may be swung open. The upper bushing and pin are retained, so they can't fall out during use.

The block accepts rigging ropes of up to 3/4" diameter, and tree rigging slings up to 1" . The load rating on the block is 33,720 lb MBS (150 kN), with a WLL of 6,744 lb (30 kN) at a 5:1 design factor. The surfaces of this block are rounded to be more rope-friendly. The sheaves are larger than other 3/4" block for a better bend radius in your rigging lines.

This arborist block is recommended for professional use in medium to heavy tree rigging. The combination of good design and strength is unbeatable at this price.


  • Manufacturer: ISC
  • Maximum rope diameter: 19mm (3/4")
  • Tensile strength: 150 kN (33,721 lb)
  • Material: anodized aluminum
  • Weight: 2.3kg (5 lb
  • (more...)

Ratings & Reviews

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10/15/2023 7:50 pm

This is my most-used rigging block

by John -

It is strong, light enough, easy to open and close with no loose parts, and has functioned well handling dynamic and static loads since 2016. It also still looks new even with all the use.