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ISC Large 3/4" Aluminum Spring Block

 ISC Large 3/4”  Aluminum Arborist Block
ISC Large 3/4 Aluminum Spring Block image ISC Large 3/4" Aluminum Spring Block

Buy ISC Large 3/4” Aluminum Spring Block

Block + Loopie

The ISC large 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 sideplates 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 45,000 lb MBS (200 kN), with a WLL of 9,000 lb (40 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 large to heavy tree rigging. The combination of good design and strength is unbeatable at this price.

Purchase this kit as a package with a 3/4” x 2-8’ Loopie sling and save.

  • Oversized upper sheave accepts 1” slings
  • Captive upper sheave with spring-lock
  • Wide bend radius on lower sheave
  • Improved machining for rope-friendly surfaces
  • Sintered bronze bushings
  • Powder-coated side plates
Made in: UK
MBS: 45,000 lb / 200 kN
WLL (5:1) / (10:1): 9,000 lb / 4,500 lb
Max Rope Diameter:3/4”
Max Sling Diameter: 1”
Sideplate Material:Powder-coated aluminum
Sheave Material:Aluminum
Axle Material: Stainless Steel
Upper Sheave Diameter: 2”
Lower Sheave Diameter: 3.81”
Height: 11.375”
Width: 6.375”
Weight: 7.62 lb

Each ISC Large 3/4” large arborist block is individually serial-numbered.


  • CE Approved

ANSI Z133-2017

The American National Standards Institute (ANSI) has released the ANSI Z133 safety requirements which apply to arboricultural operations. Components of a rigging system must be used within their Working Load Limits.

ISC blocks are ANSI compliant when used within the manufacturer Working Load Limits.

A green log weight chart (found in the Samson Rigging Wheel) will aid in determining loads in tree rigging.

The full ANSI Z133 safety requirements are available on our tree care standards page.

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