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CMI 1” Arborist Block

 1” Arborist Block  1” Arborist Block by CMI  1” Arborist Block by CMI  1” Arborist Block by CMI
CMI 1” Arborist Block image CMI 1” Arborist Block

Buy CMI 1” Arborist Block

CMI 1 ” Arborist Block
Block with 3/4” x 2-8’ Loopie

Finally, a bigger arborist block is available at better price. CMI has made a great oversized aluminum block with a maximum capacity of 1” and an impressive MBS of 68,000 lb. and manufacturer working load limit of 13,600 lb - over 6 tons. For years the only 1” we could offer cost almost $500. The 1” arborist block allows you to run your biggest ropes through hardware that can handle similarly big loads. This block from the makers of our bestselling stainless steel arborist block is a big 9.25” x 6” yet weighs in at only 6.6 lb.

The block swings open yet the upper sheave is retained so there is no risk of losing it while installing your sling, and you can fit up to a 1” sling for really big jobs. The lower sheave will give you a proper bend radius for 3/4” and larger rope (though it is a bit tight on 1”). The block features anodized aluminum sideplates, an aluminum sheave, bushing, and stainless steel axle.

  • Largest block
  • 1” capacity
  • Impressive strength
  • Anodized sideplates
  • Aluminum sheave
  • Bushing
  • Stainless axle
Manufacturer : CMI
Made in : USA
Break Strength : 68,000 lb
WLL : 13,600 lb
Max Rope Size : 1” (25mm)
Weighs : 6.5 lb (2.9 kg)
Height : 9.25” (23.5 cm)
Width : 6” (15.25 cm)

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.

The CMI 1” Block is 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.

Customer Reviews

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Rated: Excellent Review by: John Edward Delgado

“I use this equipment for log extraction form forest - using 1" bull rope w/ working end braided loop and choker cable on log. My first pull was a 24" x 24' log and uphill to boot! - Like a dream like a dream she came up with hardly any effort. Like this product so much, I ordered another on the next day for if/when I have to redirect 2 runs. Get the loopie sling with this you will not be sorry - worth it's weight ... ”

Rated: Excellent for 3/4” Ropes & 1” Slings Review by: Niceguydave

“I started testing on this new block from CMI about a month ago. I have been on the hunt for a 1" block for a while, not so much for being able to use a 1 rigging line, but to be able to put a proper sized sling in the block to build a good anchor.

This block weighs 6.4 pounds, not overly heavy. Finish is good - anodized aluminum. It is pretty much an updated Hobbs block.


  • It will take a 1 Tenex Loopie sling
  • WLL of 13,600 pounds
  • MBS of 68,000 pounds

Cons: If 1 rope is used it will stick out past the cheeks - not good. Bend radius is a little too skinny IMO for 7/8” - 1” ropes.

Overall I like this block. It is an excellent rigging option for 3/4” lines and seems build to take the beating so often encountered in negative blocking.”

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