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The seaHorse is the world's first ISA 51 certified HighTech HighlineWeblock with the best PreTension-Ability, made from a single piece of aluminum and has a versatile HollowCenterDiverter. This WebLock also impresses with its low weight and, at the same time, the generous dimensioning, which allows comfortable handling (even with up to 8mm thick slackline webbing).

Availability: In stock

Best PreTension-Ability Weblock with Double-Pin - seaHorse 1.5

According to ISA 51 Standard tested and certified Highline Weblock

The seaHorse is the most sophisticated weblock on the market. The new design adds versatility, new functions, and a low weight. The seaHorse is forged from a single piece of aircraft aluminium, which allows it to be really strong and lightweight.

The biggest innovation is the hollow center diverter. The hollow center diverter allows a variety of soft connections. This can be really useful when building a HangOver pulley system, attaching a regular pulley system, or attaching a rope to train for highlines in the park. We even built in some grooves that keep your soft attachments in place instead of sliding up. Note: the hollow center diverter cannot be used to anchor the seahorse.

The geometry of the seaHorse is optimised for the most efficient pretensioning possible. A lot of testing with a big modular plate has led to the perfect dimensions for a HangOver pulley system. To see how to create the lightest 15:1 system on the market, you can watch the video above!

The two pins are connected with a rubber connection cord which is less likely to get entangled around the pins while tensioning the line.


  • Working Load Limit (WLL) 12kN, MBS:70kN
  • Designed for slacklines of 25-27mm wide (20mm with spacers)
  • ball locking pin (d=11.1mm, weight optimized) out of high alloy, stainless steel (17-4PH)
  • made from aircraft aluminium 7075-T6 in SLACKTIVITY-Green
  • hot forged from one piece
  • 36mm HollowCenterDiverter (HCD) works like a riggingplate!
  • Weight: 260g
  • tested and certified according to ISA 51standard

Before using this equipment, you must read and understand all instructions for Use! Check the manual (PDF) on "Manual (pdf)". And make sure to use the anti-slippage knot as explained in the manual by every rigg!

It is important to us from SLACKTIVITY to pass on the necessary know-how to our customers with the material they buy. That is why we make the manuals as clear, simple and visually appealing as possible. Please have a look! If you still have any questions, we are happy to help. And check out for more information an tutorial the SLACKTIVITY Youtube-Channel.

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