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Auto Block & Hollow Block

posted Mar 1, 2013, 11:33 PM by Ken Buscho   [ updated Feb 8, 2019, 5:06 PM ]

An Auto Block is a friction device made out of the same type of cord used for a Prusik. Rather than tying the ends together in DFK, the ours are sewn together.  The portion stitched is then sealed with a clear material to let you inspect the stitching.  Because it's stitched, it is less bulky, uses less rope and is lighter weight.  The one in our kit is made out of 6mm accessory cord and is stitched into an 11" prusik.  For care of this component, see this document:

The picture at the left shows the cord in use in a prusik knot.  A more standard definition of the knot has it looking like this:

Or like this, as a rappel backup knot:

Your kit might also include a Hollow Block:

This is a device produced by Sterling Rope, and is noted for its gripping power. It can be used in a fashion similar to the Auto Block. Mean Breaking Strength MBS is 3147 (14kN), giving it a working strength of 314 pounds.