Harken 16 mm Air Block with O Ring

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The 16 mm is Harken's® smallest block. It is perfect for small synthetic control lines found on high-tech dinghies.  404 block uses an O-ring to keep the line in the sheave during intermittent loading. The patented bearing system uses stainless steel balls in a captive grooved race and has a 250 lb (113 kg) safe working load - the highest on the market compared to similarly sized blocks. 

Use for: Dinghy control lines, Big Boat leech lines, Downhauls, Traveler controls, Spinnaker pole trip lines, Outhauls, Cunninghams, Halyards on prams.

Part Number: 404




Sheave Ø

5/8 in

16 mm


1 1/8 in

29 mm


0.33 oz

10 g

Max Line Ø

7/32 in

5 mm

Maximum Working Load

250 lb

113 kg

Breaking Load

1200 lb

544 kg


Need help to design your Harken system - take a look here for the Harken System Guides and Drawings

Or perhaps you need some other information (load calculators, block selectors, service instructions or manuals)?   Take a look here for all the official Harken Support Information