The autoblock and prusik are both friction hitches, but suit different roles. The autoblock (French prusik) releases easily and slides one-handed, making it ideal as a rappel backup you tend as you descend; the prusik grips harder in both directions but is tough to release under load, better for ascending.
| Aspect | Autoblock | Prusik |
|---|---|---|
| Main use | Rappel backup | Ascending, backup |
| Releases under load | Easily | Hard |
| Sliding | One-handed | Two hands |
| Grip strength | Moderate | Strong (both ways) |
| Tended while moving | Yes | No |
Use an autoblock when…
- You're backing up a rappel
- You want to tend it as you descend
- You want easy one-handed release
Use a prusik when…
- You're ascending a rope
- You want maximum, bidirectional grip
- You need a grab-and-hold backup
Verdict
Frequently asked questions
What's the difference between an autoblock and a prusik?
Both grip the rope, but the autoblock is designed to release and slide easily even under load, which suits tending it while rappelling. A prusik grips harder and can be tough to release once weighted, making it better for ascending.
Which is better for a rappel backup?
The autoblock, because it slides one-handed as you descend and releases easily if it grabs, letting you tend it smoothly. A prusik can grab so hard it's difficult to release mid-rappel.
How many wraps does an autoblock need?
Usually about four to six wraps, adjusted to the rope and cord so it grips reliably without being too tight to slide. Always test it under body weight before committing to the rappel.