A single block protects you where you are. Move past an obstruction and you have to disconnect, which is the moment protection stops. The twin block solves that the way a twin-tail lanyard does, but with the retraction and short arrest distance of a block: two independent legs, so one stays attached while the other is moved past the obstacle.
That makes it the right equipment for progressing along a structure with regular obstructions — lattice towers, pipework runs, gantries with uprights — where a single block would mean repeatedly unclipping.
Note the **100 kg maximum user weight**, lower than the 140 kg of most of the range, which reflects the twin construction and 25 mm webbing.
Key Features
- Two independent legs: Continuous attachment while moving past obstacles. One leg always connected.
- Retracting legs: No slack webbing, and a much shorter arrest distance than a twin-tail lanyard.
- Aluminium casing: Lighter than a steel-cased unit, which matters on a block worn on the harness rather than anchored overhead.
- Fall indicator in the swivel snap hook.
- 2 m travel per leg: Sufficient reach to move between anchor points on a structure.
- 25 mm webbing: Narrow and compact for a twin unit.
- Resistance 15 kN, BS EN 360.
Technical Specifications
| Property |
Value |
| Product Code |
FA 20 500 02 |
| Configuration |
Twin leg retractable block |
| Travel |
2 m per leg |
| Webbing |
25 mm polyester |
| Casing |
Aluminium |
| Swivel |
x1 rotation |
| Use |
Vertical only |
| Resistance |
15 kN |
| Maximum User Weight |
100 kg including equipment |
| Conformity |
BS EN 360 |
Maximum user weight is 100 kg, lower than the 140 kg of the single blocks. Check this against user weight plus tools.
BS EN 360 | Twin Leg | VERTICAL USE ONLY | Max User 100 kg | Category III PPE
Conforms to BS EN 360 for retractable type fall arresters. Vertical use only: the anchor must be overhead. Maximum user weight 100 kg including tools and equipment, lower than most blocks in this range. Category III PPE under Regulation (EU) 2016/425, covered by EU Type-Examination certificate 2777/10967-01 E01-01. Inspection by a competent person at intervals not exceeding 12 months and immediate withdrawal after arresting a fall.
Suitable Applications
The twin block suits progression along structures with regular obstructions where continuous attachment matters: lattice towers and masts, pipework and process plant, gantries and walkways with uprights, and structural steel with frequent bracing. It is worn on the harness with the legs clipped ahead, rather than anchored overhead in one position. Where the work happens in one place, a single block is lighter and cheaper and takes a heavier user.
More About This Product
A retractable block is the most mechanically complex item in a typical fall protection kit, and the only one the user cannot inspect internally. Everything else — harness, lanyard, connectors — can be examined by eye and hand. A block is a sealed case containing a spring, a drum, a brake and a fall indicator, and the user sees none of it.
That is why the pre-use checks matter so much. Winding the line fully out, feeling it retract, testing the lock with a sharp pull and checking the fall indicator are the only windows into whether the mechanism still works. They take under a minute and they are the difference between a working block and a heavy metal box.
Clearance, Edges and the Horizontal Question
Three things determine whether a block is the right choice, and all three are commonly got wrong.
Clearance. A block arrests in a much shorter distance than a lanyard, which is usually why it is chosen. But the arrest distance is not zero: it is the deceleration distance plus the user's height below the attachment point plus a safety margin. On a short block over a low structure the numbers get tight quickly, and the block's own datasheet gives the figure to work from.
Edges. Where the line can cross an edge in a fall, the edge becomes the failure point. A wire rope line will be cut by a sharp steel edge under fall arrest load as readily as webbing. Blocks specifically rated for leading edge use exist and are constructed differently; a standard block used over an edge is being used outside its approval.
Horizontal use. Most retractable blocks require an overhead anchor and are not approved for horizontal work. On a deck, a roof or a gantry the anchor is often at or below foot level, which changes both the fall factor and the way the line runs. Only a block specifically marked for horizontal use may be used that way, and it is not something to infer from the model name or the supplier's category page.
How to Use the Twin Block
- Keep one leg attached at all times: Clip the second before releasing the first. That is the entire purpose.
- Never clip the free leg back to the harness: As with a twin-tail lanyard, a leg clipped to the harness transmits arrest forces directly to the user.
- Anchor overhead: Vertical use only.
- Check both fall indicators before use.
- Check the 100 kg limit: User plus tools. Lower than most blocks and easy to exceed with a loaded tool belt.
- Test both legs lock: Each leg independently.
Warning: Maximum user weight is 100 kg including tools, lower than most blocks in this range. Vertical use only. Never clip the unused leg back to the harness. Never move both legs at once.
Safety Information
- For use only by trained and competent persons within a safe system of work.
- Maximum user weight 100 kg including tools and equipment.
- Vertical use only. Anchor must be overhead.
- One leg must remain attached at all times.
- Never clip the free leg back to the harness.
- Check both fall indicators and test both legs before every use.
- Withdraw immediately if either fall indicator has triggered.
- Do not open the casing or attempt repair.
- Inspection by a competent person required at intervals not exceeding 12 months.
Inspection and Maintenance
Twice the work of a single block, since both legs need checking independently. Pull each leg fully out and inspect the whole webbing length on both faces for cuts, abrasion and fraying, then let each retract under control confirming full smooth return. Test the locking action on each leg separately, since one can fail while the other works. Check both fall indicators, the aluminium casing for cracks and impact damage, and both snap hooks for gate operation and throat wear. A twin block that has arrested a fall on either leg is withdrawn entirely.
Downloads
Frequently Asked Questions
Q: Twin block or twin-tail lanyard?
Both keep you attached while moving. The block retracts, so no slack hangs around your legs, and it arrests a fall in a much shorter distance, needing less clearance below. The lanyard is cheaper, lighter and has no mechanism. On a structure with limited clearance, the block is the better answer.
Q: Why is the user weight limit lower?
100 kg against 140 kg on the single blocks, reflecting the twin construction and 25 mm webbing. It is worth checking against actual user weight plus tools, since a loaded tool belt can be 10 to 15 kg and the margin is smaller than people assume.
Q: Can I move both legs at once?
No. That leaves you unattached, which defeats the entire purpose of a twin system. Clip the second before releasing the first, every time.
