100 mm Black Magic® AirBlocks® are used on offshore boats where weight and performance are critical. They feature free-rolling, large-diameter aluminum sheaves with Torlon® roller bearings housed in a unique center cage. UV-resistant, carbon-black Delrin® balls carry sideloads. Corrosion is minimized by isolating dissimilar metals.

Blocks are Hardkote-anodized and have 17-4 PH stainless headposts and shackles. Easily disassembled. Use it for sheets, halyards, running backstays and control lines.

Part Number: 3254
**Replaces 3012

Imperial Metric
Sheave Dia. 4" 100 mm
Length 7 11/16" 195 mm
Weight w/Shackle 31.18 oz 884 gr
Max Line Dia. 5/8" 16 mm
Maximum Working Load 7500 lbs 3402 kg
Breaking Load 15000 lbs 6804 kg


A 3 21/32" 93 mm
B 3 27/32" 97 mm
C 2 5/16" 59 mm

* Includes padeye. Uses hole spacing and base dimensions of HAR648 padeye.

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Harken 100mm Standup Block
Original Price: $ 778.35
Price: $ 684.95
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