The sliding X and the quad are two ways to rig a self-adjusting two-point anchor. The sliding X uses a twisted sling to follow the load but can extend and shock-load if a point fails; the quad uses a doubled loop with limiter knots that cap extension and keep redundancy. The quad is the modern favourite.
| Aspect | Sliding X | Quad |
|---|---|---|
| Rigging | Twisted sling | Doubled loop + limiter knots |
| Adjusts to pull | Yes | Yes (limited) |
| If a point fails | Extends, shock-loads | Limited extension, stays redundant |
| Redundancy | Weaker | Strong |
| Setup | Quick, minimal gear | Pre-tieable, reusable |
Use a sliding X when…
- You need a quick two-point rig with minimal gear
- You add limiter knots to cap extension
- You're improvising from a single sling
Use a quad when…
- You're rigging fixed two-bolt anchors
- You want limited extension and redundancy
- You want a reusable, pre-tied rig
Verdict
Frequently asked questions
What's the difference between a sliding X and a quad?
Both self-adjust to the direction of pull, but the sliding X can extend and shock-load the remaining point if one fails, while the quad's limiter knots cap that extension and keep the anchor redundant. The quad is generally considered the safer modern rig.
Is the sliding X safe?
It equalizes well but has a known weakness: extension and shock-loading if a point fails. Adding limiter (overhand) knots greatly improves it, but many climbers now prefer the quad for two-point anchors for this reason.
What are limiter knots?
Limiter knots are overhand knots tied in the sling or cord on either side of the master point to cap how far it can slide if a piece fails, reducing extension and shock-loading. They're essential on a sliding X and built into the quad.
Related: Sliding X · Quad · Anchor · Equalization