Gear You Ought to Know is a series that showcases underrated, underappreciated, or just plain innovative gear in a discussion-based format. If there’s a piece of gear you’d like to see featured, contact us.

Climbing is an inherently dangerous sport.

This disclaimer is printed on the packaging of every piece of gear we purchase. But what about rappelling?

Sterling Hollow Block ReviewRappelling is likely the biggest cause of easily preventable deaths within our sport. Between rappelling off the ends of unknotted ropes, losing control during descent, and improper loading of rappel devices, an unfortunate number of climbers lose their lives in the act.

Every climber should be knotting their ends on most, if not all, rappels and using an autoblocking backup. This autoblocking backup, a key to preventing fatal rappel errors, often gets overlooked. Many climbers simply delegate a small piece of cord or a sling to do the job, when actually, the best tool for the job is Sterling Rope’s Hollow Block (HollowBlock).

Sterling Hollow Block Hollowblock Rappel


Features and benefits of Sterling’s Hollow Block

While rappelling, climbers face a constant tradeoff between ease of sliding their friction hitch/backup knot and the knot’s ability to lock up when left untended. The Hollow Block makes this tradeoff a thing of the past.


Related: 4 Reasons Why You Should Always Carry a Prusik on Your Harness


True to its name, the Hollow Block lacks a core, allowing it to lock up on anything you manage to wrap it around, then unlocks with ease. The Aramid fibers used in its construction resist heat damage up to 900 degrees—almost double the melting point of nylon. Its length is ideal for attaching to your leg loop, preventing the risk of the knot being sucked into your rappel device and causing a catastrophic failure. Finally, the Hollow Block’s sewn ends maintain a low profile and eliminate the unnecessary bulk of tied accessory cord.
sterling_hollow_block_rope-minSterling’s Hollow Block is truly a purpose-built piece of gear, specifically designed to keep climbers safe while rappelling. Not only easier to use, it is also significantly safer than any alternative methods. The Hollow Block can be used to tie either a Prusik knot, or a Klemheist knot. We have found that the Klemheist is easier to tie, dress, and untie, though it does not grip the rope as aggressively as the Prusik.

The Hollow Block is such an improvement over standard accessory cord that world-renowned ice climber Will Gadd includes it when discussing his Minimalist Mandatory Gear. However, a love of Hollow Blocks is not limited to the elites of the climbing world: the Hollow Block has a rating of 4.9 out of 5 stars on Amazon and a majority of 5-star endorsements on Backcountry.

One reviewer calls it

a must-have addition to any climbing harness,

while another reported the Hollow Block’s ability to lock up on both 3/4″ PVC pipe and 5mm rope! The benefits of the Hollow Block are so significant that I will not leave the ground without it. Pick one up and enjoy the extra margin of safety during your next rappel.

Close Up Sterling Hollow Block Hollowblock

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